Backup data from S3 cloud

Hi,

I have a department who have already got an amount of data on the S3 cloud and they are asking if this can be backed up to tape/disk for off-site storage, I know that NBU can be used to backup and restore from S3 but not sure how I would go about getting data from S3 that has not been backed up via NBU, can the S3 be seen as a client?

We are using NetBackup Enterprise 7.5.0.7 

Rgds,

Kev