"The aim of this type of mission is to intercept a potentially suspect aircraft or one that is going to invade Baltic airspace without having been coordinated," says Commander Mathieu at Siauliai air base in Lithuania. Set up after the Baltic states joined NATO in 2004, the 'sky police' were reinforced in 2014 after the annexation of Crimea by Russia and are currently operating, in the midst of the war in Ukraine, with three rotating deployments from the allied countries. This NATO force protects Lithuania, Latvia and Estonia, former Soviet republics which do not have the air resources to defend themselves. IMAGES AND SOUNDBITES ARRANGED IN SEQUENCES N°36QY9AL