The A-10A single-seat variant was the only version produced, though one pre-production airframe was modified into the YA-10B twin-seat prototype to test an all-weather night capable version. In 2005, a program was started to upgrade the remaining A-10A aircraft to the A-10C configuration, with modern avionics for use with precision weaponry. The U.S. Air Force had stated the F-35 would replace the A-10 as it entered service, but this remains highly contentious within the USAF and in political circles. With a variety of upgrades and wing replacements, the A-10's service life can be extended to 2040; the service has no planned retirement date .