reason for this decision to retain the ability to destroy deeply buried hard targets.

In the late 80's, a life extension program for the B-53 was begun, which included upgrades to the safing equipment. The new earth-penetrating B-61 modification, the Mod 11, began entering service in January 1997 and is replacing the B-53 in active service. Under current plans the B-53 will be retained indefinitely as part of the hedge stockpile