The aim of the article is to explore the situation when a state air border is crossed by civil and state-owned authorized and unauthorized aircrafts. Ways of influencing aircraft likely to make an unauthorized crossing are also presented. In addition, the article describes cooperation procedures applied by civil and military operational services during the Air POLICING mission. In accordance with the Convention on International Civil Aviation, civil aircraft may cross an air border in the airspace once the need to adapt to the requirements of the airspace in which the aircraft performs air operations is met. However, the entry of a foreign state aircraft into the airspace is possible after a special clearance has been granted and must be carried out in accordance with the terms of such clearance. The article also discusses the actions taken when the aircraft crosses the air border in a manner inconsistent with the conditions or performs an air operation contrary to the clearance of the air traffic services units and procedures adopted by national and international civilian and military organizations.