diff --git a/CHANGELOG_PENDING.md b/CHANGELOG_PENDING.md
index 8a1927a39ca..621f7210248 100644
--- a/CHANGELOG_PENDING.md
+++ b/CHANGELOG_PENDING.md
@@ -1,5 +1,26 @@
 ### SDK Features
 
 ### SDK Enhancements
+* `aws/endpoints`: Adds support for STS Regional Flags ([#2779](https://github.com/aws/aws-sdk-go/pull/2779))
+  * Implements STS regional flag, with support for `legacy` and `regional` options. Defaults to `legacy`. Legacy, will force all regions specified in aws/endpoints/sts_legacy_regions.go to resolve to the STS global endpoint, sts.amazonaws.com. This is the SDK's current behavior.
+  * When the flag's value is `regional` the SDK will resolve the endpoint based on the endpoints.json model. This allows STS to update their service's modeled endpoints to be regionalized for all regions. When `regional` turned on use `aws-global` as the region to use the global endpoint.
+  * `AWS_STS_REGIONAL_ENDPOINTS=regional` for environment, or `sts_regional_endpoints=regional` in shared config file.
+  * The regions the SDK defaults to the STS global endpoint in `legacy` mode are: 
+    * ap-northeast-1
+    * ap-south-1
+    * ap-southeast-1
+    * ap-southeast-2
+    * aws-global
+    * ca-central-1
+    * eu-central-1
+    * eu-north-1
+    * eu-west-1
+    * eu-west-2
+    * eu-west-3
+    * sa-east-1
+    * us-east-1
+    * us-east-2
+    * us-west-1
+    * us-west-2
 
 ### SDK Bugs
diff --git a/aws/client/default_retryer.go b/aws/client/default_retryer.go
index 0fda42510f0..9f6af19dd45 100644
--- a/aws/client/default_retryer.go
+++ b/aws/client/default_retryer.go
@@ -16,11 +16,11 @@ import (
 type DefaultRetryer struct {
 	// Num max Retries is the number of max retries that will be performed.
 	// By default, this is zero.
-	NumMaxRetries    int
+	NumMaxRetries int
 
 	// MinRetryDelay is the minimum retry delay after which retry will be performed.
 	// If not set, the value is 0ns.
-	MinRetryDelay    time.Duration
+	MinRetryDelay time.Duration
 
 	// MinThrottleRetryDelay is the minimum retry delay when throttled.
 	// If not set, the value is 0ns.
@@ -28,7 +28,7 @@ type DefaultRetryer struct {
 
 	// MaxRetryDelay is the maximum retry delay before which retry must be performed.
 	// If not set, the value is 0ns.
-	MaxRetryDelay    time.Duration
+	MaxRetryDelay time.Duration
 
 	// MaxThrottleDelay is the maximum retry delay when throttled.
 	// If not set, the value is 0ns.
diff --git a/aws/client/default_retryer_test.go b/aws/client/default_retryer_test.go
index 08d9ee7cdd5..b8794f3ccc8 100644
--- a/aws/client/default_retryer_test.go
+++ b/aws/client/default_retryer_test.go
@@ -166,7 +166,7 @@ func TestGetRetryDelay(t *testing.T) {
 }
 
 func TestRetryDelay(t *testing.T) {
-	d := DefaultRetryer{NumMaxRetries:100}
+	d := DefaultRetryer{NumMaxRetries: 100}
 	r := request.Request{}
 	for i := 0; i < 100; i++ {
 		rTemp := r
diff --git a/aws/config.go b/aws/config.go
index fd1e240f6eb..8a7699b9619 100644
--- a/aws/config.go
+++ b/aws/config.go
@@ -246,6 +246,9 @@ type Config struct {
 	// Disabling this feature is useful when you want to use local endpoints
 	// for testing that do not support the modeled host prefix pattern.
 	DisableEndpointHostPrefix *bool
+
+	// STSRegionalEndpoint will enable regional or legacy endpoint resolving
+	STSRegionalEndpoint endpoints.STSRegionalEndpoint
 }
 
 // NewConfig returns a new Config pointer that can be chained with builder
@@ -420,6 +423,13 @@ func (c *Config) MergeIn(cfgs ...*Config) {
 	}
 }
 
+// WithSTSRegionalEndpoint will set whether or not to use regional endpoint flag
+// when resolving the endpoint for a service
+func (c *Config) WithSTSRegionalEndpoint(sre endpoints.STSRegionalEndpoint) *Config {
+	c.STSRegionalEndpoint = sre
+	return c
+}
+
 func mergeInConfig(dst *Config, other *Config) {
 	if other == nil {
 		return
@@ -520,6 +530,10 @@ func mergeInConfig(dst *Config, other *Config) {
 	if other.DisableEndpointHostPrefix != nil {
 		dst.DisableEndpointHostPrefix = other.DisableEndpointHostPrefix
 	}
+
+	if other.STSRegionalEndpoint != endpoints.UnsetSTSEndpoint {
+		dst.STSRegionalEndpoint = other.STSRegionalEndpoint
+	}
 }
 
 // Copy will return a shallow copy of the Config object. If any additional
diff --git a/aws/endpoints/endpoints.go b/aws/endpoints/endpoints.go
index 9c936be6cf9..c06901efa43 100644
--- a/aws/endpoints/endpoints.go
+++ b/aws/endpoints/endpoints.go
@@ -3,6 +3,7 @@ package endpoints
 import (
 	"fmt"
 	"regexp"
+	"strings"
 
 	"github.com/aws/aws-sdk-go/aws/awserr"
 )
@@ -46,6 +47,43 @@ type Options struct {
 	//
 	// This option is ignored if StrictMatching is enabled.
 	ResolveUnknownService bool
+
+	// STS Regional Endpoint flag helps with resolving the STS endpoint
+	STSRegionalEndpoint STSRegionalEndpoint
+}
+
+// STSRegionalEndpoint is an enum type alias for int
+// It is used internally by the core sdk as STS Regional Endpoint flag value
+type STSRegionalEndpoint int
+
+const (
+
+	// UnsetSTSEndpoint represents that STS Regional Endpoint flag is not specified.
+	UnsetSTSEndpoint STSRegionalEndpoint = iota
+
+	// LegacySTSEndpoint represents when STS Regional Endpoint flag is specified
+	// to use legacy endpoints.
+	LegacySTSEndpoint
+
+	// RegionalSTSEndpoint represents when STS Regional Endpoint flag is specified
+	// to use regional endpoints.
+	RegionalSTSEndpoint
+)
+
+// GetSTSRegionalEndpoint function returns the STSRegionalEndpointFlag based
+// on the input string provided in env config or shared config by the user.
+//
+// `legacy`, `regional` are the only case-insensitive valid strings for
+// resolving the STS regional Endpoint flag.
+func GetSTSRegionalEndpoint(s string) (STSRegionalEndpoint, error) {
+	switch {
+	case strings.EqualFold(s, "legacy"):
+		return LegacySTSEndpoint, nil
+	case strings.EqualFold(s, "regional"):
+		return RegionalSTSEndpoint, nil
+	default:
+		return UnsetSTSEndpoint, fmt.Errorf("unable to resolve the value of STSRegionalEndpoint for %v", s)
+	}
 }
 
 // Set combines all of the option functions together.
@@ -79,6 +117,12 @@ func ResolveUnknownServiceOption(o *Options) {
 	o.ResolveUnknownService = true
 }
 
+// STSRegionalEndpointOption enables the STS endpoint resolver behavior to resolve
+// STS endpoint to their regional endpoint, instead of the global endpoint.
+func STSRegionalEndpointOption(o *Options) {
+	o.STSRegionalEndpoint = RegionalSTSEndpoint
+}
+
 // A Resolver provides the interface for functionality to resolve endpoints.
 // The build in Partition and DefaultResolver return value satisfy this interface.
 type Resolver interface {
@@ -194,7 +238,7 @@ func (p Partition) ID() string { return p.id }
 // require the provided service and region to be known by the partition.
 // If the endpoint cannot be strictly resolved an error will be returned. This
 // mode is useful to ensure the endpoint resolved is valid. Without
-// StrictMatching enabled the endpoint returned my look valid but may not work.
+// StrictMatching enabled the endpoint returned may look valid but may not work.
 // StrictMatching requires the SDK to be updated if you want to take advantage
 // of new regions and services expansions.
 //
diff --git a/aws/endpoints/sts_legacy_regions.go b/aws/endpoints/sts_legacy_regions.go
new file mode 100644
index 00000000000..68ed2d9e25f
--- /dev/null
+++ b/aws/endpoints/sts_legacy_regions.go
@@ -0,0 +1,20 @@
+package endpoints
+
+var stsLegacyGlobalRegions = map[string]struct{}{
+	"ap-northeast-1": {},
+	"ap-south-1":     {},
+	"ap-southeast-1": {},
+	"ap-southeast-2": {},
+	"aws-global":     {},
+	"ca-central-1":   {},
+	"eu-central-1":   {},
+	"eu-north-1":     {},
+	"eu-west-1":      {},
+	"eu-west-2":      {},
+	"eu-west-3":      {},
+	"sa-east-1":      {},
+	"us-east-1":      {},
+	"us-east-2":      {},
+	"us-west-1":      {},
+	"us-west-2":      {},
+}
diff --git a/aws/endpoints/v3model.go b/aws/endpoints/v3model.go
index 523ad79ac0a..49a3a398847 100644
--- a/aws/endpoints/v3model.go
+++ b/aws/endpoints/v3model.go
@@ -79,6 +79,12 @@ func (p partition) EndpointFor(service, region string, opts ...func(*Options)) (
 	var opt Options
 	opt.Set(opts...)
 
+	if service == "sts" && opt.STSRegionalEndpoint != RegionalSTSEndpoint {
+		if _, ok := stsLegacyGlobalRegions[region]; ok {
+			region = "aws-global"
+		}
+	}
+
 	s, hasService := p.Services[service]
 	if !(hasService || opt.ResolveUnknownService) {
 		// Only return error if the resolver will not fallback to creating
@@ -92,6 +98,7 @@ func (p partition) EndpointFor(service, region string, opts ...func(*Options)) (
 	}
 
 	defs := []endpoint{p.Defaults, s.Defaults}
+
 	return e.resolve(service, region, p.DNSSuffix, defs, opt), nil
 }
 
diff --git a/aws/endpoints/v3model_shared_test.go b/aws/endpoints/v3model_shared_test.go
new file mode 100644
index 00000000000..b0b00b14ea3
--- /dev/null
+++ b/aws/endpoints/v3model_shared_test.go
@@ -0,0 +1,69 @@
+package endpoints
+
+import "regexp"
+
+var testPartitions = partitions{
+	partition{
+		ID:        "part-id",
+		Name:      "partitionName",
+		DNSSuffix: "amazonaws.com",
+		RegionRegex: regionRegex{
+			Regexp: func() *regexp.Regexp {
+				reg, _ := regexp.Compile("^(us|eu|ap|sa|ca)\\-\\w+\\-\\d+$")
+				return reg
+			}(),
+		},
+		Defaults: endpoint{
+			Hostname:          "{service}.{region}.{dnsSuffix}",
+			Protocols:         []string{"https"},
+			SignatureVersions: []string{"v4"},
+		},
+		Regions: regions{
+			"us-east-1": region{
+				Description: "region description",
+			},
+			"us-west-2": region{},
+		},
+		Services: services{
+			"s3": service{},
+			"service1": service{
+				Defaults: endpoint{
+					CredentialScope: credentialScope{
+						Service: "service1",
+					},
+				},
+				Endpoints: endpoints{
+					"us-east-1": {},
+					"us-west-2": {
+						HasDualStack:      boxedTrue,
+						DualStackHostname: "{service}.dualstack.{region}.{dnsSuffix}",
+					},
+				},
+			},
+			"service2": service{
+				Defaults: endpoint{
+					CredentialScope: credentialScope{
+						Service: "service2",
+					},
+				},
+			},
+			"httpService": service{
+				Defaults: endpoint{
+					Protocols: []string{"http"},
+				},
+			},
+			"globalService": service{
+				IsRegionalized:    boxedFalse,
+				PartitionEndpoint: "aws-global",
+				Endpoints: endpoints{
+					"aws-global": endpoint{
+						CredentialScope: credentialScope{
+							Region: "us-east-1",
+						},
+						Hostname: "globalService.amazonaws.com",
+					},
+				},
+			},
+		},
+	},
+}
diff --git a/aws/endpoints/v3model_sts_regional_test.go b/aws/endpoints/v3model_sts_regional_test.go
new file mode 100644
index 00000000000..aa6784a897a
--- /dev/null
+++ b/aws/endpoints/v3model_sts_regional_test.go
@@ -0,0 +1,582 @@
+// +build go1.7
+
+package endpoints
+
+import (
+	"regexp"
+	"testing"
+)
+
+func TestEndpointFor_STSRegionalFlag(t *testing.T) {
+
+	// mock STS regional endpoints model
+	mockSTSModelPartition := partition{
+		ID:        "aws",
+		Name:      "AWS Standard",
+		DNSSuffix: "amazonaws.com",
+		RegionRegex: regionRegex{
+			Regexp: func() *regexp.Regexp {
+				reg, _ := regexp.Compile("^(us|eu|ap|sa|ca|me)\\-\\w+\\-\\d+$")
+				return reg
+			}(),
+		},
+		Defaults: endpoint{
+			Hostname:          "{service}.{region}.{dnsSuffix}",
+			Protocols:         []string{"https"},
+			SignatureVersions: []string{"v4"},
+		},
+		Regions: regions{
+			"ap-east-1": region{
+				Description: "Asia Pacific (Hong Kong)",
+			},
+			"ap-northeast-1": region{
+				Description: "Asia Pacific (Tokyo)",
+			},
+			"ap-northeast-2": region{
+				Description: "Asia Pacific (Seoul)",
+			},
+			"ap-south-1": region{
+				Description: "Asia Pacific (Mumbai)",
+			},
+			"ap-southeast-1": region{
+				Description: "Asia Pacific (Singapore)",
+			},
+			"ap-southeast-2": region{
+				Description: "Asia Pacific (Sydney)",
+			},
+			"ca-central-1": region{
+				Description: "Canada (Central)",
+			},
+			"eu-central-1": region{
+				Description: "EU (Frankfurt)",
+			},
+			"eu-north-1": region{
+				Description: "EU (Stockholm)",
+			},
+			"eu-west-1": region{
+				Description: "EU (Ireland)",
+			},
+			"eu-west-2": region{
+				Description: "EU (London)",
+			},
+			"eu-west-3": region{
+				Description: "EU (Paris)",
+			},
+			"me-south-1": region{
+				Description: "Middle East (Bahrain)",
+			},
+			"sa-east-1": region{
+				Description: "South America (Sao Paulo)",
+			},
+			"us-east-1": region{
+				Description: "US East (N. Virginia)",
+			},
+			"us-east-2": region{
+				Description: "US East (Ohio)",
+			},
+			"us-west-1": region{
+				Description: "US West (N. California)",
+			},
+			"us-west-2": region{
+				Description: "US West (Oregon)",
+			},
+		},
+		Services: services{
+			"sts": service{
+				PartitionEndpoint: "aws-global",
+				Defaults:          endpoint{},
+				Endpoints: endpoints{
+					"ap-east-1":      endpoint{},
+					"ap-northeast-1": endpoint{},
+					"ap-northeast-2": endpoint{},
+					"ap-south-1":     endpoint{},
+					"ap-southeast-1": endpoint{},
+					"ap-southeast-2": endpoint{},
+					"aws-global": endpoint{
+						Hostname: "sts.amazonaws.com",
+						CredentialScope: credentialScope{
+							Region: "us-east-1",
+						},
+					},
+					"ca-central-1": endpoint{},
+					"eu-central-1": endpoint{},
+					"eu-north-1":   endpoint{},
+					"eu-west-1":    endpoint{},
+					"eu-west-2":    endpoint{},
+					"eu-west-3":    endpoint{},
+					"me-south-1":   endpoint{},
+					"sa-east-1":    endpoint{},
+					"us-east-1":    endpoint{},
+					"us-east-1-fips": endpoint{
+						Hostname: "sts-fips.us-east-1.amazonaws.com",
+						CredentialScope: credentialScope{
+							Region: "us-east-1",
+						},
+					},
+					"us-east-2": endpoint{},
+					"us-east-2-fips": endpoint{
+						Hostname: "sts-fips.us-east-2.amazonaws.com",
+						CredentialScope: credentialScope{
+							Region: "us-east-2",
+						},
+					},
+					"us-west-1": endpoint{},
+					"us-west-1-fips": endpoint{
+						Hostname: "sts-fips.us-west-1.amazonaws.com",
+						CredentialScope: credentialScope{
+							Region: "us-west-1",
+						},
+					},
+					"us-west-2": endpoint{},
+					"us-west-2-fips": endpoint{
+						Hostname: "sts-fips.us-west-2.amazonaws.com",
+						CredentialScope: credentialScope{
+							Region: "us-west-2",
+						},
+					},
+				},
+			},
+		},
+	}
+
+	// resolver for mock STS regional endpoints model
+	resolver := mockSTSModelPartition
+
+	cases := map[string]struct {
+		service, region                                     string
+		regional                                            bool
+		ExpectURL, ExpectSigningMethod, ExpectSigningRegion string
+		ExpectSigningNameDerived                            bool
+	}{
+		// STS Endpoints resolver tests :
+		"sts/us-west-2/regional": {
+			service:                  "sts",
+			region:                   "us-west-2",
+			regional:                 true,
+			ExpectURL:                "https://sts.us-west-2.amazonaws.com",
+			ExpectSigningMethod:      "v4",
+			ExpectSigningNameDerived: true,
+			ExpectSigningRegion:      "us-west-2",
+		},
+		"sts/us-west-2/legacy": {
+			service:                  "sts",
+			region:                   "us-west-2",
+			regional:                 false,
+			ExpectURL:                "https://sts.amazonaws.com",
+			ExpectSigningMethod:      "v4",
+			ExpectSigningNameDerived: true,
+			ExpectSigningRegion:      "us-east-1",
+		},
+		"sts/ap-east-1/regional": {
+			service:                  "sts",
+			region:                   "ap-east-1",
+			regional:                 true,
+			ExpectURL:                "https://sts.ap-east-1.amazonaws.com",
+			ExpectSigningMethod:      "v4",
+			ExpectSigningNameDerived: true,
+			ExpectSigningRegion:      "ap-east-1",
+		},
+		"sts/ap-east-1/legacy": {
+			service:                  "sts",
+			region:                   "ap-east-1",
+			regional:                 false,
+			ExpectURL:                "https://sts.ap-east-1.amazonaws.com",
+			ExpectSigningMethod:      "v4",
+			ExpectSigningNameDerived: true,
+			ExpectSigningRegion:      "ap-east-1",
+		},
+		"sts/us-west-2-fips/regional": {
+			service:                  "sts",
+			region:                   "us-west-2-fips",
+			regional:                 true,
+			ExpectURL:                "https://sts-fips.us-west-2.amazonaws.com",
+			ExpectSigningMethod:      "v4",
+			ExpectSigningNameDerived: true,
+			ExpectSigningRegion:      "us-west-2",
+		},
+		"sts/us-west-2-fips/legacy": {
+			service:                  "sts",
+			region:                   "us-west-2-fips",
+			regional:                 false,
+			ExpectURL:                "https://sts-fips.us-west-2.amazonaws.com",
+			ExpectSigningMethod:      "v4",
+			ExpectSigningNameDerived: true,
+			ExpectSigningRegion:      "us-west-2",
+		},
+		"sts/aws-global/regional": {
+			service:                  "sts",
+			region:                   "aws-global",
+			regional:                 true,
+			ExpectURL:                "https://sts.amazonaws.com",
+			ExpectSigningMethod:      "v4",
+			ExpectSigningNameDerived: true,
+			ExpectSigningRegion:      "us-east-1",
+		},
+		"sts/aws-global/legacy": {
+			service:                  "sts",
+			region:                   "aws-global",
+			regional:                 false,
+			ExpectURL:                "https://sts.amazonaws.com",
+			ExpectSigningMethod:      "v4",
+			ExpectSigningNameDerived: true,
+			ExpectSigningRegion:      "us-east-1",
+		},
+		"sts/ap-south-1/regional": {
+			service:                  "sts",
+			region:                   "ap-south-1",
+			regional:                 true,
+			ExpectURL:                "https://sts.ap-south-1.amazonaws.com",
+			ExpectSigningMethod:      "v4",
+			ExpectSigningNameDerived: true,
+			ExpectSigningRegion:      "ap-south-1",
+		},
+		"sts/ap-south-1/legacy": {
+			service:                  "sts",
+			region:                   "ap-south-1",
+			regional:                 false,
+			ExpectURL:                "https://sts.amazonaws.com",
+			ExpectSigningMethod:      "v4",
+			ExpectSigningNameDerived: true,
+			ExpectSigningRegion:      "us-east-1",
+		},
+		"sts/ap-northeast-1/regional": {
+			service:                  "sts",
+			region:                   "ap-northeast-1",
+			regional:                 true,
+			ExpectURL:                "https://sts.ap-northeast-1.amazonaws.com",
+			ExpectSigningMethod:      "v4",
+			ExpectSigningNameDerived: true,
+			ExpectSigningRegion:      "ap-northeast-1",
+		},
+		"sts/ap-northeast-1/legacy": {
+			service:                  "sts",
+			region:                   "ap-northeast-1",
+			regional:                 false,
+			ExpectURL:                "https://sts.amazonaws.com",
+			ExpectSigningMethod:      "v4",
+			ExpectSigningNameDerived: true,
+			ExpectSigningRegion:      "us-east-1",
+		},
+		"sts/ap-southeast-1/regional": {
+			service:                  "sts",
+			region:                   "ap-southeast-1",
+			regional:                 true,
+			ExpectURL:                "https://sts.ap-southeast-1.amazonaws.com",
+			ExpectSigningMethod:      "v4",
+			ExpectSigningNameDerived: true,
+			ExpectSigningRegion:      "ap-southeast-1",
+		},
+		"sts/ap-southeast-1/legacy": {
+			service:                  "sts",
+			region:                   "ap-southeast-1",
+			regional:                 false,
+			ExpectURL:                "https://sts.amazonaws.com",
+			ExpectSigningMethod:      "v4",
+			ExpectSigningNameDerived: true,
+			ExpectSigningRegion:      "us-east-1",
+		},
+		"sts/ca-central-1/regional": {
+			service:                  "sts",
+			region:                   "ca-central-1",
+			regional:                 true,
+			ExpectURL:                "https://sts.ca-central-1.amazonaws.com",
+			ExpectSigningMethod:      "v4",
+			ExpectSigningNameDerived: true,
+			ExpectSigningRegion:      "ca-central-1",
+		},
+		"sts/ca-central-1/legacy": {
+			service:                  "sts",
+			region:                   "ca-central-1",
+			regional:                 false,
+			ExpectURL:                "https://sts.amazonaws.com",
+			ExpectSigningMethod:      "v4",
+			ExpectSigningNameDerived: true,
+			ExpectSigningRegion:      "us-east-1",
+		},
+		"sts/eu-central-1/regional": {
+			service:                  "sts",
+			region:                   "eu-central-1",
+			regional:                 true,
+			ExpectURL:                "https://sts.eu-central-1.amazonaws.com",
+			ExpectSigningMethod:      "v4",
+			ExpectSigningNameDerived: true,
+			ExpectSigningRegion:      "eu-central-1",
+		},
+		"sts/eu-central-1/legacy": {
+			service:                  "sts",
+			region:                   "eu-central-1",
+			regional:                 false,
+			ExpectURL:                "https://sts.amazonaws.com",
+			ExpectSigningMethod:      "v4",
+			ExpectSigningNameDerived: true,
+			ExpectSigningRegion:      "us-east-1",
+		},
+		"sts/eu-north-1/regional": {
+			service:                  "sts",
+			region:                   "eu-north-1",
+			regional:                 true,
+			ExpectURL:                "https://sts.eu-north-1.amazonaws.com",
+			ExpectSigningMethod:      "v4",
+			ExpectSigningNameDerived: true,
+			ExpectSigningRegion:      "eu-north-1",
+		},
+		"sts/eu-north-1/legacy": {
+			service:                  "sts",
+			region:                   "eu-north-1",
+			regional:                 false,
+			ExpectURL:                "https://sts.amazonaws.com",
+			ExpectSigningMethod:      "v4",
+			ExpectSigningNameDerived: true,
+			ExpectSigningRegion:      "us-east-1",
+		},
+		"sts/eu-west-1/regional": {
+			service:                  "sts",
+			region:                   "eu-west-1",
+			regional:                 true,
+			ExpectURL:                "https://sts.eu-west-1.amazonaws.com",
+			ExpectSigningMethod:      "v4",
+			ExpectSigningNameDerived: true,
+			ExpectSigningRegion:      "eu-west-1",
+		},
+		"sts/eu-west-1/legacy": {
+			service:                  "sts",
+			region:                   "eu-west-1",
+			regional:                 false,
+			ExpectURL:                "https://sts.amazonaws.com",
+			ExpectSigningMethod:      "v4",
+			ExpectSigningNameDerived: true,
+			ExpectSigningRegion:      "us-east-1",
+		},
+		"sts/eu-west-2/regional": {
+			service:                  "sts",
+			region:                   "eu-west-2",
+			regional:                 true,
+			ExpectURL:                "https://sts.eu-west-2.amazonaws.com",
+			ExpectSigningMethod:      "v4",
+			ExpectSigningNameDerived: true,
+			ExpectSigningRegion:      "eu-west-2",
+		},
+		"sts/eu-west-2/legacy": {
+			service:                  "sts",
+			region:                   "eu-west-2",
+			regional:                 false,
+			ExpectURL:                "https://sts.amazonaws.com",
+			ExpectSigningMethod:      "v4",
+			ExpectSigningNameDerived: true,
+			ExpectSigningRegion:      "us-east-1",
+		},
+		"sts/eu-west-3/regional": {
+			service:                  "sts",
+			region:                   "eu-west-3",
+			regional:                 true,
+			ExpectURL:                "https://sts.eu-west-3.amazonaws.com",
+			ExpectSigningMethod:      "v4",
+			ExpectSigningNameDerived: true,
+			ExpectSigningRegion:      "eu-west-3",
+		},
+		"sts/eu-west-3/legacy": {
+			service:                  "sts",
+			region:                   "eu-west-3",
+			regional:                 false,
+			ExpectURL:                "https://sts.amazonaws.com",
+			ExpectSigningMethod:      "v4",
+			ExpectSigningNameDerived: true,
+			ExpectSigningRegion:      "us-east-1",
+		},
+		"sts/sa-east-1/regional": {
+			service:                  "sts",
+			region:                   "sa-east-1",
+			regional:                 true,
+			ExpectURL:                "https://sts.sa-east-1.amazonaws.com",
+			ExpectSigningMethod:      "v4",
+			ExpectSigningNameDerived: true,
+			ExpectSigningRegion:      "sa-east-1",
+		},
+		"sts/sa-east-1/legacy": {
+			service:                  "sts",
+			region:                   "sa-east-1",
+			regional:                 false,
+			ExpectURL:                "https://sts.amazonaws.com",
+			ExpectSigningMethod:      "v4",
+			ExpectSigningNameDerived: true,
+			ExpectSigningRegion:      "us-east-1",
+		},
+		"sts/us-east-1/regional": {
+			service:                  "sts",
+			region:                   "us-east-1",
+			regional:                 true,
+			ExpectURL:                "https://sts.us-east-1.amazonaws.com",
+			ExpectSigningMethod:      "v4",
+			ExpectSigningNameDerived: true,
+			ExpectSigningRegion:      "us-east-1",
+		},
+		"sts/us-east-1/legacy": {
+			service:                  "sts",
+			region:                   "us-east-1",
+			regional:                 false,
+			ExpectURL:                "https://sts.amazonaws.com",
+			ExpectSigningMethod:      "v4",
+			ExpectSigningNameDerived: true,
+			ExpectSigningRegion:      "us-east-1",
+		},
+		"sts/us-east-2/regional": {
+			service:                  "sts",
+			region:                   "us-east-2",
+			regional:                 true,
+			ExpectURL:                "https://sts.us-east-2.amazonaws.com",
+			ExpectSigningMethod:      "v4",
+			ExpectSigningNameDerived: true,
+			ExpectSigningRegion:      "us-east-2",
+		},
+		"sts/us-east-2/legacy": {
+			service:                  "sts",
+			region:                   "us-east-2",
+			regional:                 false,
+			ExpectURL:                "https://sts.amazonaws.com",
+			ExpectSigningMethod:      "v4",
+			ExpectSigningNameDerived: true,
+			ExpectSigningRegion:      "us-east-1",
+		},
+		"sts/us-west-1/regional": {
+			service:                  "sts",
+			region:                   "us-west-1",
+			regional:                 true,
+			ExpectURL:                "https://sts.us-west-1.amazonaws.com",
+			ExpectSigningMethod:      "v4",
+			ExpectSigningNameDerived: true,
+			ExpectSigningRegion:      "us-west-1",
+		},
+		"sts/us-west-1/legacy": {
+			service:                  "sts",
+			region:                   "us-west-1",
+			regional:                 false,
+			ExpectURL:                "https://sts.amazonaws.com",
+			ExpectSigningMethod:      "v4",
+			ExpectSigningNameDerived: true,
+			ExpectSigningRegion:      "us-east-1",
+		},
+	}
+
+	for name, c := range cases {
+		t.Run(name, func(t *testing.T) {
+			var optionSlice []func(o *Options)
+			optionSlice = append(optionSlice, func(o *Options) {
+				if c.regional {
+					o.STSRegionalEndpoint = RegionalSTSEndpoint
+				}
+			})
+
+			actual, err := resolver.EndpointFor(c.service, c.region, optionSlice...)
+			if err != nil {
+				t.Fatalf("failed to resolve endpoint, %v", err)
+			}
+
+			if e, a := c.ExpectURL, actual.URL; e != a {
+				t.Errorf("expect %v, got %v", e, a)
+			}
+
+			if e, a := c.ExpectSigningMethod, actual.SigningMethod; e != a {
+				t.Errorf("expect %v, got %v", e, a)
+			}
+
+			if e, a := c.ExpectSigningNameDerived, actual.SigningNameDerived; e != a {
+				t.Errorf("expect %v, got %v", e, a)
+			}
+
+			if e, a := c.ExpectSigningRegion, actual.SigningRegion; e != a {
+				t.Errorf("expect %v, got %v", e, a)
+			}
+
+		})
+	}
+}
+
+func TestSTSRegionalEndpoint_CNPartition(t *testing.T) {
+	mockSTSCNPartition := partition{
+		ID:        "aws-cn",
+		Name:      "AWS China",
+		DNSSuffix: "amazonaws.com.cn",
+		RegionRegex: regionRegex{
+			Regexp: func() *regexp.Regexp {
+				reg, _ := regexp.Compile("^cn\\-\\w+\\-\\d+$")
+				return reg
+			}(),
+		},
+		Defaults: endpoint{
+			Hostname:          "{service}.{region}.{dnsSuffix}",
+			Protocols:         []string{"https"},
+			SignatureVersions: []string{"v4"},
+		},
+		Regions: regions{
+			"cn-north-1": region{
+				Description: "China (Beijing)",
+			},
+			"cn-northwest-1": region{
+				Description: "China (Ningxia)",
+			},
+		},
+		Services: services{
+			"sts": service{
+				Endpoints: endpoints{
+					"cn-north-1":     endpoint{},
+					"cn-northwest-1": endpoint{},
+				},
+			},
+		},
+	}
+
+	resolver := mockSTSCNPartition
+
+	cases := map[string]struct {
+		service, region                                     string
+		regional                                            bool
+		ExpectURL, ExpectSigningMethod, ExpectSigningRegion string
+		ExpectSigningNameDerived                            bool
+	}{
+		"sts/cn-north-1/regional": {
+			service:                  "sts",
+			region:                   "cn-north-1",
+			regional:                 true,
+			ExpectURL:                "https://sts.cn-north-1.amazonaws.com.cn",
+			ExpectSigningMethod:      "v4",
+			ExpectSigningNameDerived: true,
+			ExpectSigningRegion:      "cn-north-1",
+		},
+		"sts/cn-north-1/legacy": {
+			service:                  "sts",
+			region:                   "cn-north-1",
+			regional:                 false,
+			ExpectURL:                "https://sts.cn-north-1.amazonaws.com.cn",
+			ExpectSigningMethod:      "v4",
+			ExpectSigningNameDerived: true,
+			ExpectSigningRegion:      "cn-north-1",
+		},
+	}
+
+	for name, c := range cases {
+		var optionSlice []func(o *Options)
+		t.Run(name, func(t *testing.T) {
+			if c.regional {
+				optionSlice = append(optionSlice, STSRegionalEndpointOption)
+			}
+			actual, err := resolver.EndpointFor(c.service, c.region, optionSlice...)
+			if err != nil {
+				t.Fatalf("failed to resolve endpoint, %v", err)
+			}
+
+			if e, a := c.ExpectURL, actual.URL; e != a {
+				t.Errorf("expect %v, got %v", e, a)
+			}
+			if e, a := c.ExpectSigningMethod, actual.SigningMethod; e != a {
+				t.Errorf("expect %v, got %v", e, a)
+			}
+			if e, a := c.ExpectSigningNameDerived, actual.SigningNameDerived; e != a {
+				t.Errorf("expect %v, got %v", e, a)
+			}
+			if e, a := c.ExpectSigningRegion, actual.SigningRegion; e != a {
+				t.Errorf("expect %v, got %v", e, a)
+			}
+		})
+	}
+
+}
diff --git a/aws/endpoints/v3model_test.go b/aws/endpoints/v3model_test.go
index 0b8b00673d7..fc782a26717 100644
--- a/aws/endpoints/v3model_test.go
+++ b/aws/endpoints/v3model_test.go
@@ -1,3 +1,5 @@
+// +build go1.7
+
 package endpoints
 
 import (
@@ -253,72 +255,6 @@ func TestEndpointMergeIn(t *testing.T) {
 	}
 }
 
-var testPartitions = partitions{
-	partition{
-		ID:        "part-id",
-		Name:      "partitionName",
-		DNSSuffix: "amazonaws.com",
-		RegionRegex: regionRegex{
-			Regexp: func() *regexp.Regexp {
-				reg, _ := regexp.Compile("^(us|eu|ap|sa|ca)\\-\\w+\\-\\d+$")
-				return reg
-			}(),
-		},
-		Defaults: endpoint{
-			Hostname:          "{service}.{region}.{dnsSuffix}",
-			Protocols:         []string{"https"},
-			SignatureVersions: []string{"v4"},
-		},
-		Regions: regions{
-			"us-east-1": region{
-				Description: "region description",
-			},
-			"us-west-2": region{},
-		},
-		Services: services{
-			"s3": service{},
-			"service1": service{
-				Defaults: endpoint{
-					CredentialScope: credentialScope{
-						Service: "service1",
-					},
-				},
-				Endpoints: endpoints{
-					"us-east-1": {},
-					"us-west-2": {
-						HasDualStack:      boxedTrue,
-						DualStackHostname: "{service}.dualstack.{region}.{dnsSuffix}",
-					},
-				},
-			},
-			"service2": service{
-				Defaults: endpoint{
-					CredentialScope: credentialScope{
-						Service: "service2",
-					},
-				},
-			},
-			"httpService": service{
-				Defaults: endpoint{
-					Protocols: []string{"http"},
-				},
-			},
-			"globalService": service{
-				IsRegionalized:    boxedFalse,
-				PartitionEndpoint: "aws-global",
-				Endpoints: endpoints{
-					"aws-global": endpoint{
-						CredentialScope: credentialScope{
-							Region: "us-east-1",
-						},
-						Hostname: "globalService.amazonaws.com",
-					},
-				},
-			},
-		},
-	},
-}
-
 func TestResolveEndpoint(t *testing.T) {
 	resolved, err := testPartitions.EndpointFor("service2", "us-west-2")
 
@@ -539,3 +475,67 @@ func TestResolveEndpoint_AwsGlobal(t *testing.T) {
 		t.Errorf("expect the signing name to be derived")
 	}
 }
+
+func TestEndpointFor_RegionalFlag(t *testing.T) {
+	// AwsPartition resolver for STS regional endpoints in AWS Partition
+	resolver := AwsPartition()
+
+	cases := map[string]struct {
+		service, region                                     string
+		regional                                            bool
+		ExpectURL, ExpectSigningMethod, ExpectSigningRegion string
+		ExpectSigningNameDerived                            bool
+	}{
+		"acm/ap-northeast-1/regional": {
+			service:                  "acm",
+			region:                   "ap-northeast-1",
+			regional:                 true,
+			ExpectURL:                "https://acm.ap-northeast-1.amazonaws.com",
+			ExpectSigningMethod:      "v4",
+			ExpectSigningNameDerived: true,
+			ExpectSigningRegion:      "ap-northeast-1",
+		},
+		"acm/ap-northeast-1/legacy": {
+			service:                  "acm",
+			region:                   "ap-northeast-1",
+			regional:                 false,
+			ExpectURL:                "https://acm.ap-northeast-1.amazonaws.com",
+			ExpectSigningMethod:      "v4",
+			ExpectSigningNameDerived: true,
+			ExpectSigningRegion:      "ap-northeast-1",
+		},
+	}
+
+	for name, c := range cases {
+		t.Run(name, func(t *testing.T) {
+			var optionSlice []func(o *Options)
+			optionSlice = append(optionSlice, func(o *Options) {
+				if c.regional {
+					o.STSRegionalEndpoint = RegionalSTSEndpoint
+				}
+			})
+
+			actual, err := resolver.EndpointFor(c.service, c.region, optionSlice...)
+			if err != nil {
+				t.Fatalf("failed to resolve endpoint, %v", err)
+			}
+
+			if e, a := c.ExpectURL, actual.URL; e != a {
+				t.Errorf("expect %v, got %v", e, a)
+			}
+
+			if e, a := c.ExpectSigningMethod, actual.SigningMethod; e != a {
+				t.Errorf("expect %v, got %v", e, a)
+			}
+
+			if e, a := c.ExpectSigningNameDerived, actual.SigningNameDerived; e != a {
+				t.Errorf("expect %v, got %v", e, a)
+			}
+
+			if e, a := c.ExpectSigningRegion, actual.SigningRegion; e != a {
+				t.Errorf("expect %v, got %v", e, a)
+			}
+
+		})
+	}
+}
diff --git a/aws/session/csm_test.go b/aws/session/csm_test.go
index 0ed1c03a37b..90da22bc700 100644
--- a/aws/session/csm_test.go
+++ b/aws/session/csm_test.go
@@ -101,7 +101,10 @@ func TestSession_loadCSMConfig(t *testing.T) {
 				os.Setenv(name, v)
 			}
 
-			envCfg := loadEnvConfig()
+			envCfg, err := loadEnvConfig()
+			if err != nil {
+				t.Fatalf("failed to load the envcfg, %v", err)
+			}
 			csmCfg, err := loadCSMConfig(envCfg, c.ConfigFiles)
 			if len(c.Err) != 0 {
 				if err == nil {
diff --git a/aws/session/env_config.go b/aws/session/env_config.go
index 60a6f9ce2a4..530cc3a9c06 100644
--- a/aws/session/env_config.go
+++ b/aws/session/env_config.go
@@ -1,12 +1,14 @@
 package session
 
 import (
+	"fmt"
 	"os"
 	"strconv"
 
 	"github.com/aws/aws-sdk-go/aws"
 	"github.com/aws/aws-sdk-go/aws/credentials"
 	"github.com/aws/aws-sdk-go/aws/defaults"
+	"github.com/aws/aws-sdk-go/aws/endpoints"
 )
 
 // EnvProviderName provides a name of the provider when config is loaded from environment.
@@ -125,6 +127,12 @@ type envConfig struct {
 	//
 	//  AWS_ROLE_SESSION_NAME=session_name
 	RoleSessionName string
+
+	// Specifies the Regional Endpoint flag for the sdk to resolve the endpoint for a service
+	//
+	// AWS_STS_REGIONAL_ENDPOINTS =sts_regional_endpoint
+	// This can take value as `regional` or `legacy`
+	STSRegionalEndpoint endpoints.STSRegionalEndpoint
 }
 
 var (
@@ -179,6 +187,9 @@ var (
 	roleSessionNameEnvKey = []string{
 		"AWS_ROLE_SESSION_NAME",
 	}
+	stsRegionalEndpointKey = []string{
+		"AWS_STS_REGIONAL_ENDPOINTS",
+	}
 )
 
 // loadEnvConfig retrieves the SDK's environment configuration.
@@ -187,7 +198,7 @@ var (
 // If the environment variable `AWS_SDK_LOAD_CONFIG` is set to a truthy value
 // the shared SDK config will be loaded in addition to the SDK's specific
 // configuration values.
-func loadEnvConfig() envConfig {
+func loadEnvConfig() (envConfig, error) {
 	enableSharedConfig, _ := strconv.ParseBool(os.Getenv("AWS_SDK_LOAD_CONFIG"))
 	return envConfigLoad(enableSharedConfig)
 }
@@ -198,11 +209,11 @@ func loadEnvConfig() envConfig {
 // Loads the shared configuration in addition to the SDK's specific configuration.
 // This will load the same values as `loadEnvConfig` if the `AWS_SDK_LOAD_CONFIG`
 // environment variable is set.
-func loadSharedEnvConfig() envConfig {
+func loadSharedEnvConfig() (envConfig, error) {
 	return envConfigLoad(true)
 }
 
-func envConfigLoad(enableSharedConfig bool) envConfig {
+func envConfigLoad(enableSharedConfig bool) (envConfig, error) {
 	cfg := envConfig{}
 
 	cfg.EnableSharedConfig = enableSharedConfig
@@ -264,12 +275,23 @@ func envConfigLoad(enableSharedConfig bool) envConfig {
 
 	cfg.CustomCABundle = os.Getenv("AWS_CA_BUNDLE")
 
-	return cfg
+	// STS Regional Endpoint variable
+	for _, k := range stsRegionalEndpointKey {
+		if v := os.Getenv(k); len(v) != 0 {
+			STSRegionalEndpoint, err := endpoints.GetSTSRegionalEndpoint(v)
+			if err != nil {
+				return cfg, fmt.Errorf("failed to load, %v from env config, %v", k, err)
+			}
+			cfg.STSRegionalEndpoint = STSRegionalEndpoint
+		}
+	}
+
+	return cfg, nil
 }
 
 func setFromEnvVal(dst *string, keys []string) {
 	for _, k := range keys {
-		if v := os.Getenv(k); len(v) > 0 {
+		if v := os.Getenv(k); len(v) != 0 {
 			*dst = v
 			break
 		}
diff --git a/aws/session/env_config_test.go b/aws/session/env_config_test.go
index 03e4b4949e5..5d5e37ae49d 100644
--- a/aws/session/env_config_test.go
+++ b/aws/session/env_config_test.go
@@ -84,7 +84,10 @@ func TestLoadEnvConfig_Creds(t *testing.T) {
 				os.Setenv(k, v)
 			}
 
-			cfg := loadEnvConfig()
+			cfg, err := loadEnvConfig()
+			if err != nil {
+				t.Fatalf("failed to load env config, %v", err)
+			}
 			if !reflect.DeepEqual(c.Val, cfg.Creds) {
 				t.Errorf("expect credentials to match.\n%s",
 					awstesting.SprintExpectActual(c.Val, cfg.Creds))
@@ -279,10 +282,17 @@ func TestLoadEnvConfig(t *testing.T) {
 			}
 
 			var cfg envConfig
+			var err error
 			if c.UseSharedConfigCall {
-				cfg = loadSharedEnvConfig()
+				cfg, err = loadSharedEnvConfig()
+				if err != nil {
+					t.Errorf("failed to load shared env config, %v", err)
+				}
 			} else {
-				cfg = loadEnvConfig()
+				cfg, err = loadEnvConfig()
+				if err != nil {
+					t.Errorf("failed to load env config, %v", err)
+				}
 			}
 
 			if !reflect.DeepEqual(c.Config, cfg) {
diff --git a/aws/session/session.go b/aws/session/session.go
index 7b0a942e223..245a5fb1bac 100644
--- a/aws/session/session.go
+++ b/aws/session/session.go
@@ -73,7 +73,7 @@ type Session struct {
 // func is called instead of waiting to receive an error until a request is made.
 func New(cfgs ...*aws.Config) *Session {
 	// load initial config from environment
-	envCfg := loadEnvConfig()
+	envCfg, envErr := loadEnvConfig()
 
 	if envCfg.EnableSharedConfig {
 		var cfg aws.Config
@@ -93,17 +93,17 @@ func New(cfgs ...*aws.Config) *Session {
 			// Session creation failed, need to report the error and prevent
 			// any requests from succeeding.
 			s = &Session{Config: defaults.Config()}
-			s.Config.MergeIn(cfgs...)
-			s.Config.Logger.Log("ERROR:", msg, "Error:", err)
-			s.Handlers.Validate.PushBack(func(r *request.Request) {
-				r.Error = err
-			})
+			s.logDeprecatedNewSessionError(msg, err, cfgs)
 		}
 
 		return s
 	}
 
 	s := deprecatedNewSession(cfgs...)
+	if envErr != nil {
+		msg := "failed to load env config"
+		s.logDeprecatedNewSessionError(msg, envErr, cfgs)
+	}
 
 	if csmCfg, err := loadCSMConfig(envCfg, []string{}); err != nil {
 		if l := s.Config.Logger; l != nil {
@@ -112,11 +112,8 @@ func New(cfgs ...*aws.Config) *Session {
 	} else if csmCfg.Enabled {
 		err := enableCSM(&s.Handlers, csmCfg, s.Config.Logger)
 		if err != nil {
-			err = fmt.Errorf("failed to enable CSM, %v", err)
-			s.Config.Logger.Log("ERROR:", err.Error())
-			s.Handlers.Validate.PushBack(func(r *request.Request) {
-				r.Error = err
-			})
+			msg := "failed to enable CSM"
+			s.logDeprecatedNewSessionError(msg, err, cfgs)
 		}
 	}
 
@@ -279,10 +276,17 @@ type Options struct {
 //     }))
 func NewSessionWithOptions(opts Options) (*Session, error) {
 	var envCfg envConfig
+	var err error
 	if opts.SharedConfigState == SharedConfigEnable {
-		envCfg = loadSharedEnvConfig()
+		envCfg, err = loadSharedEnvConfig()
+		if err != nil {
+			return nil, fmt.Errorf("failed to load shared config, %v", err)
+		}
 	} else {
-		envCfg = loadEnvConfig()
+		envCfg, err = loadEnvConfig()
+		if err != nil {
+			return nil, fmt.Errorf("failed to load environment config, %v", err)
+		}
 	}
 
 	if len(opts.Profile) != 0 {
@@ -550,6 +554,9 @@ func mergeConfigSrcs(cfg, userCfg *aws.Config,
 		}
 	}
 
+	// Regional Endpoint flag for STS endpoint resolving
+	mergeSTSRegionalEndpointConfig(cfg, envCfg, sharedCfg)
+
 	// Configure credentials if not already set by the user when creating the
 	// Session.
 	if cfg.Credentials == credentials.AnonymousCredentials && userCfg.Credentials == nil {
@@ -563,6 +570,22 @@ func mergeConfigSrcs(cfg, userCfg *aws.Config,
 	return nil
 }
 
+// mergeSTSRegionalEndpointConfig function merges the STSRegionalEndpoint into cfg from
+// envConfig and SharedConfig with envConfig being given precedence over SharedConfig
+func mergeSTSRegionalEndpointConfig(cfg *aws.Config, envCfg envConfig, sharedCfg sharedConfig) error {
+
+	cfg.STSRegionalEndpoint = envCfg.STSRegionalEndpoint
+
+	if cfg.STSRegionalEndpoint == endpoints.UnsetSTSEndpoint {
+		cfg.STSRegionalEndpoint = sharedCfg.STSRegionalEndpoint
+	}
+
+	if cfg.STSRegionalEndpoint == endpoints.UnsetSTSEndpoint {
+		cfg.STSRegionalEndpoint = endpoints.LegacySTSEndpoint
+	}
+	return nil
+}
+
 func initHandlers(s *Session) {
 	// Add the Validate parameter handler if it is not disabled.
 	s.Handlers.Validate.Remove(corehandlers.ValidateParametersHandler)
@@ -616,6 +639,9 @@ func (s *Session) clientConfigWithErr(serviceName string, cfgs ...*aws.Config) (
 			func(opt *endpoints.Options) {
 				opt.DisableSSL = aws.BoolValue(s.Config.DisableSSL)
 				opt.UseDualStack = aws.BoolValue(s.Config.UseDualStack)
+				// Support for STSRegionalEndpoint where the STSRegionalEndpoint is
+				// provided in envconfig or sharedconfig with envconfig getting precedence.
+				opt.STSRegionalEndpoint = s.Config.STSRegionalEndpoint
 
 				// Support the condition where the service is modeled but its
 				// endpoint metadata is not available.
@@ -658,3 +684,14 @@ func (s *Session) ClientConfigNoResolveEndpoint(cfgs ...*aws.Config) client.Conf
 		SigningName:        resolved.SigningName,
 	}
 }
+
+// logDeprecatedNewSessionError function enables error handling for session
+func (s *Session) logDeprecatedNewSessionError(msg string, err error, cfgs []*aws.Config) {
+	// Session creation failed, need to report the error and prevent
+	// any requests from succeeding.
+	s.Config.MergeIn(cfgs...)
+	s.Config.Logger.Log("ERROR:", msg, "Error:", err)
+	s.Handlers.Validate.PushBack(func(r *request.Request) {
+		r.Error = err
+	})
+}
diff --git a/aws/session/shared_config.go b/aws/session/shared_config.go
index d91ac93a544..8574668960b 100644
--- a/aws/session/shared_config.go
+++ b/aws/session/shared_config.go
@@ -5,6 +5,7 @@ import (
 
 	"github.com/aws/aws-sdk-go/aws/awserr"
 	"github.com/aws/aws-sdk-go/aws/credentials"
+	"github.com/aws/aws-sdk-go/aws/endpoints"
 	"github.com/aws/aws-sdk-go/internal/ini"
 )
 
@@ -40,6 +41,9 @@ const (
 	// Web Identity Token File
 	webIdentityTokenFileKey = `web_identity_token_file` // optional
 
+	// Additional config fields for regional or legacy endpoints
+	stsRegionalEndpointSharedKey = `sts_regional_endpoints`
+
 	// DefaultSharedConfigProfile is the default profile to be used when
 	// loading configuration from the config files if another profile name
 	// is not provided.
@@ -82,12 +86,17 @@ type sharedConfig struct {
 	//
 	//	endpoint_discovery_enabled = true
 	EnableEndpointDiscovery *bool
-
 	// CSM Options
 	CSMEnabled  *bool
 	CSMHost     string
 	CSMPort     string
 	CSMClientID string
+
+	// Specifies the Regional Endpoint flag for the sdk to resolve the endpoint for a service
+	//
+	// sts_regional_endpoints = sts_regional_endpoint
+	// This can take value as `LegacySTSEndpoint` or `RegionalSTSEndpoint`
+	STSRegionalEndpoint endpoints.STSRegionalEndpoint
 }
 
 type sharedConfigFile struct {
@@ -244,8 +253,16 @@ func (cfg *sharedConfig) setFromIniFile(profile string, file sharedConfigFile, e
 		updateString(&cfg.RoleSessionName, section, roleSessionNameKey)
 		updateString(&cfg.SourceProfileName, section, sourceProfileKey)
 		updateString(&cfg.CredentialSource, section, credentialSourceKey)
-
 		updateString(&cfg.Region, section, regionKey)
+
+		if v := section.String(stsRegionalEndpointSharedKey); len(v) != 0 {
+			sre, err := endpoints.GetSTSRegionalEndpoint(v)
+			if err != nil {
+				return fmt.Errorf("failed to load %s from shared config, %s, %v",
+					stsRegionalEndpointKey, file.Filename, err)
+			}
+			cfg.STSRegionalEndpoint = sre
+		}
 	}
 
 	updateString(&cfg.CredentialProcess, section, credentialProcessKey)
diff --git a/private/model/api/example_test.go b/private/model/api/example_test.go
index 2c7149c3752..4083ebf8abd 100644
--- a/private/model/api/example_test.go
+++ b/private/model/api/example_test.go
@@ -296,8 +296,8 @@ func ExampleFooService_Foo_shared00() {
 }
 `
 	if expected != a.ExamplesGoCode() {
-			t.Errorf("Expected:\n%s\nReceived:\n%s\n", expected, a.ExamplesGoCode())
-		}
+		t.Errorf("Expected:\n%s\nReceived:\n%s\n", expected, a.ExamplesGoCode())
+	}
 }
 
 func TestBuildShape(t *testing.T) {