How can KMS multi region keys support encryption and decryption of the same data across multiple AWS regions without needing to re encrypt data during a cross region transfer?

KMS multi region keys let you create a primary key in one region and replicate it as related keys in other regions, sharing the same underlying key material, meaning data encrypted with the primary key in one region can be decrypted directly using the replica key in another region without requiring you to decrypt and re encrypt the data during a cross region migration or in a multi region disaster recovery scenario.

aws kms replicate-key --key-id abc123 --replica-region eu-west-1