PODGORICA, Montenegro (AP) — NATO aircraft have started policing Montenegro's airspace, a year after the small Adriatic state became a member of the Western military alliance despite strong opposition from Russia.

Italian and Greek warplanes held an exercise in the skies over Montenegro's capital, Podgorica, on Tuesday. They intercepted an "intruder" aircraft and forced it to land in a symbolic start of the mission.

Defense Minister Predrag Boskovic said "from now on, our skies and the sea are protected."

Montenegro joined NATO a year ago as the military alliance's 29th member despite opposition from Moscow which considers the Adriatic country a historic Slavic ally and is opposed to NATO's enlargement.

After separating from a union with Serbia in 2006, tiny Montenegro was left without fixed-wing military aircraft. It has about a dozen operational helicopters.