The Spanish Air Force (SPAF) is the air force of Spain, founded on 7 October 1939. The Spanish Army air arm had existed since 1909, and Spanish planes fought in the Rif War in the 1920s, on both sides of the Spanish Civil War during the 1930s, the Ifni War of 1957-1958, the Yugoslav Wars, the Kosovo War, and the Libyan Civil War. Spain's air force was modernized during its alliance with NATO, taking part in some NATO interventions. In 2016, the Spanish Air Force had a strength of 20,435 personnel and 414 aircraft.