AWS Key Management Service (AWS KMS) is introducing multi-Region keys, a new capability that lets you replicate keys from one AWS Region into another. With multi-Region keys, you can more easily move encrypted data between Regions without having to decrypt and re-encrypt with different keys in each Region. Multi-Region keys are supported for client-side encryption in the AWS Encryption SDK, AWS S3 Encryption Client, and AWS DynamoDB Encryption Client. They simplify any process that copies protected data into multiple Regions, such as disaster recovery/backup, DynamoDB global tables, or for digital signature applications that require the same signing key in multiple Regions.
Source:: Amazon AWS