AWS Directory Service for Microsoft Active Directory, also known as AWS Managed Microsoft AD, and AD Connector are now available in AWS GovCloud (US-East), Amazon’s community isolated cloud infrastructure and services designed to address specific regulatory and compliance requirements of US Government agencies, as well as contractors, educational institutions, and other US customers that run sensitive workloads in the cloud.
Built from actual Microsoft Active Directory (AD), AWS Managed Microsoft AD makes it easy to migrate AD-aware applications while reducing the work of managing AD infrastructure in the AWS Cloud. You can also use your Microsoft AD credentials to connect to RDS for SQL Server instances and to sign in to AWS applications and services such as Amazon WorkSpaces. You have the flexibility to keep your identities in your existing Microsoft AD or create and manage identities in your AWS managed directory.
AD Connector is a proxy that enables AWS applications such as Amazon WorkSpaces to use use your existing on-premises AD identities without requiring AD infrastructure in the AWS Cloud. You can also use AD Connector to join Amazon EC2 instances to your on-premises AD domain and manage these instances using your existing group policy objects.
from What’s New https://aws.amazon.com/about-aws/whats-new/2019/05/aws-directory-service-for-microsoft-active-directory-and-ad-connector-are-now-available-in-the-aws-govcloud-us-east-region/