NATO Air Policing is a collective defence mission to ensure the integrity of Allies' airspace and to protect Alliance nations by maintaining continuous a 24/7 Air Policing. The mission involves the use of the Air Surveillance and Control System (ASACS), Air Command and Control (Air C2) and fighter interceptor aircraft.

These assets respond to military and civilian aircraft that do not follow international flight regulations and approach or fly near Allies' airspace. Examples are failing to identify themselves, communicate with air traffic control, or file flight plans. In such cases, NATO forces are authorised to approach the aircraft in order to identify it, establish communication if possible, and take follow-on actions if appropriate.

NATO Air Policing was created in the 1960s, as an integrated air defence structure and system, combining national and NATO assets. This allowed the nations to increase the effectiveness of individual air defence systems when protecting NATO airspace.

For NATO nations that do not have the necessary air capabilities (Albania, Estonia, Iceland, Latvia, Lithuania, Luxembourg, Montenegro, North-Macedonia and Slovenia), agreements exist to ensure a single standard of airspace security within SACEUR's area of responsibility. In the Baltic States, Air Policing capabilities were established through the deployment of NATO fighter aircraft to Šiauliai Air Base, in Lithuania, in Apr. 2004. 17 NATO nations have participated in this mission so far. Since 2004, Slovenia's airspace is covered by both Italy and Hungary. In 2009, it was agreed that Albanian airspace would be covered by Italy and Greece.

In 2014, the Alliance started enhanced Air Policing or eAP in the north and in the south as part of NATO's Assurance Measures; at the time, these measures were implemented with the goal to demonstrate the collective resolve of Allies, demonstrate the defensive nature of NATO and deter Russia from aggression or the threat of aggression against NATO Allies. 

Since then, Allied fighter jet detachments have continuously augmented the Baltic Air Policing (BAP) mission under the eAP concept in the north. The lead nation is always at Šiauliai, Lithuania, while augmenting nations fly out of Ämari, Estonia and/or Malbork, Poland. In the south, Allies have deployed their fighters to Bulgaria and Romania flying NATO Air Policing missions alongside Bulgarian and Romanian fighters.

Since Jan. 1, 2017, there has been a new Air Policing arrangement for the airspace of Belgium, the Netherlands and Luxembourg (BENELUX). The arrangement coordinated among the three Allies cover a common area of interest, the airspace of BENELUX and include provision for border-crossing activities of aircraft assigned to NATO Air Policing.

In response to Russia's invasion of Ukraine since end of Feb. 2022, NATO has substantially increased the number of fighter jets on alert across eastern Europe. Their presence helps to shield NATO against any possible aggression. Several dozen fighter jets are on alert at all time to response to possible airspace violations and to deter aggression.

Allied fighters take off from their home bases, forward deployment bases – including in the Baltic countries - and aircraft carriers flying Air Patrol missions along the Alliance's eastern flank. Allied Air Command integrates the Allied air forces' fighters, air-to-air refuelling and transport aircraft as well as Allied and NATO Airborne Warning and Control System (AWACS) platforms into the standing arrangements to safeguard the skies above the Allies. These assets enable NATO to patrol the Allied airspace and have 24/7 situational awareness above NATO and adjacent territory.