Iraq launched a full-scale invasion of Iran on 22 September 1980. The Iraqi Air Force launched surprise air strikes on ten Iranian airfields with the objective of destroying the Iranian Air Force. The attack failed to damage the Iranian Air Force significantly; it damaged some of Iran's airbase infrastructure, but failed to destroy a significant number of aircraft. The Iraqi Air Force was only able to strike in depth with a few MiG-23BN, Tu-22, and Su-20 aircraft, and Iran had built hardened aircraft shelters where most of its combat aircraft were stored.