Defense Secretary Chuck Hagel grabbed a ladder extending through the sleek black hull of the USS Tennessee at a U.S. Navy submarine base in Kings Bay and disappeared down the hatch for a close look at one of the Pentagon's most daunting budget issues.
Inside, 24 tubes for launching nuclear ballistic missiles sliced through the submarine's decks, with the crew's bunks and spartan living quarters packed around them.
The Tennessee and 13 other Ohio-class submarines are critical elements of the U.S. nuclear deterrent, but the oldest has been in service for 33 years and the end of the fleet's useful life of 42 years is in sight.