Unable to copy S3 object that have AMI from Seoul to Beijing? They are different account. And Seoul account don't have Beijing, and Beijing account don't have Seoul.

In the EC2 User Guide[1], we provide links to documentation as examples[2,3], but you must use the copy process that meets your security requirements.

I hope this helps.

Kind regards, Marilyn AWS

References:
[1] - https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ami-store-restore.html#copy-to-partition
[2] - To copy one AMI across partitions, the copy process could be as straightforward as the following: Download the object from the source bucket to an intermediate host (for example, an EC2 instance or a laptop), and then upload the object from the intermediate host to the target bucket. For each stage of the process, use the AWS credentials for the partition. -- Please access the link at [1] and then find this note to access the links for the additional documentation.
[3] - For more sustained usage, consider developing an application that manages the copies, potentially using S3 multipart downloads and uploads. -- Please access the link at [1] and then find this note to access the links for the additional documentation.