Amazon DocumentDB now supports Global Clusters in the AWS GovCloud (US-East and US-West) Regions. The AWS GovCloud (US) Regions are isolated AWS Regions designed to host sensitive data and regulated workloads in the cloud, assisting customers who have United States federal, state, or local government compliance requirements. Global Clusters in the AWS GovCloud Regions provide disaster recovery from region-wide outages and enable low-latency global reads by allowing reads from an Amazon DocumentDB cluster in the nearest AWS GovCloud Region.
Source:: Amazon AWS