The U.S. A-10 Warthog ground attack aircraft has flown more combat missions in Iraq than any other American warplane. Despite this, the U.S. Air Force has never really wanted the A-10, and has been forced to keep it because, every time a war comes around, its the A-10 that has the most work to do. While the air force wont spend any money to build a replacement for the A-10, it is under a great deal of pressure (from the army, Congress, and the small A-10 community in the air force) to upgrade about 200 of the 350 they still have (although most are in the National Guard, or in storage.) As originally built in the late 1970s, the A-10s were scheduled to be retired by 2005. But the outstanding performance of the A-10 during the 1991 Gulf War caused the air force to undertake an A-10 upgrade program that would keep several hundred of the A-10s in service for another decade, or two. The essential upgrades have to do with repairing, or replacing wing components. Without that, many of the A-10s will have to be retired because wear and tear have made them too dangerous to fly. Next comes new electronics. This includes a targeting and navigation pod, new radios and navigation gear as well as better anti-missile and anti-electronic warfare gear. New engines would be nice, as they would improve performance, but these are not essential, and are expensive. With the air force spending so much on new fighters (the F-22 and F-35), there isnt much left to keep the A-10s flying. But since the A-10s are the only warplanes that are seeing a lot of action, the air force cannot ignore the need to keep the Warthogs flying.