Starting today, Amazon EC2 C5 instances are available in the AWS GovCloud (US) Region. C5 instances, the next generation of the Amazon EC2 Compute Optimized instances powered by 3.0 GHz Intel® Xeon® Scalable processors (Skylake), were introduced in November 2017. C5 instances are built using a new light-weight hypervisor, Nitro Hypervisor, which provides practically all of the compute and memory resources to customers’ workloads.  

Source: Amazon Web Services News Amazon EC2 C5 Instances Are Now Available in the AWS GovCloud (US) Region