Italian troops will be deployed in Lithuania for the mission for the first time.
They will be safeguarding the Baltic airspace with Polish counterparts. The Italian and Polish troops are taking the mission over from Portuguese and Canadian counterparts.
NATO fighter jets have been scrambled more than 150 times this year to accompany Russian military aircraft flying near the Baltic states, which is three times more than last year. The flights of Russian military planes over the Baltic Sea without pre-arranged schedules and with their transponders switched off pose threat to civil aviation, NATO says.