Ever since the outstanding performance,  in Afghanistan, of the half century old B-52 bombers, there have been reports that the U.S. Air Force will invest still more money in upgrading the 93 B-52 still in service. These aircraft are over 40 years old, being the last ones built. Billions have been spent since then to maintain the engines and airframes, and to upgrade the electronics and weapons handling equipment. Despite their age, the "BUFFs" (Big Ugly Fat Fellas) are still much cheaper to operate than the more modern B-1 and B-2 bombers, while still having the same range and bomb carrying capacity. The ability of the air force to achieve air superiority, and defeat enemy anti-aircraft weapons, has meant that a B-52 has not been lost in combat since the Vietnam war. The current B-52s are being modified to carry a dozen JASSM (a JDAM with a motor, and a range of 300 kilometers), or 144 of the new 250 pound JDAM. The B-52s are getting better communications and fire control equipment so they can more efficiently deliver their smart bombs in support of ground troops, or at targets picked up by UAVs, satellites or commandos moving about in the enemy rear area. The well maintained B-52s are quite sturdy and have, on average, only 16,000 flying hours. The air force estimates that the B-52s won't become un-maintainable until they reach 28,000 flight hours. The B-1 and B-2 were meant to provide a high tech replacement for the B-52, but the end of the Cold War made that impractical. The kinds of anti-aircraft threats the B-1 and B-2 were designed to deal with never materialized. This left the B-52 as the most cost effective way to deliver bombs. The B-1s and B-2s are getting some of the same weapons carrying and communications upgrades as the B-52, if only because these more modern aircraft provide a more expensive backup for the B-52. The major innovation in the next generation bomber is expected to be the absence of any crew at all.