The Indian Air Force is the air arm of the Indian armed forces and the world's fourth largest air force. Its primary responsibility is to secure Indian airspace and conduct aerial warfare. The President of India is the Supreme Commander of the IAF while the Chief of Air Staff commands the force. The IAF's mission is to defend India and its interests from all airborne threats in conjunction with the other branches of the armed forces. It provides close air support to the army and strategic and tactical airlift capabilities. The IAF operates through six regional commands and two functional commands.