When creating AWS Credentials, the credentials are validated against us-east-1 which is hard coded. When validating credentials meant to be used in a different region, this validation feature is not help full:

These credentials are valid but do not have access to the "AmazonEC2" service in the region "us-east-1". This message is not a problem if you need to access to other services or to other regions. Message: "You are not authorized to perform this operation. (UnauthorizedOperation)"

It would be great if there was a selector for regions that the credentials could be validated against.