Diplomats say NATO foreign ministers are expected to invite the small Adriatic Sea country of Montenegro into the military alliance despite the objection of Russia.

NATO Secretary-General Jens Stoltenberg says Montenegro's accession is among several topics as top diplomats from its 28 member states meet Tuesday and Wednesday in Brussels. He said ministers will also discuss plans to beef up the air defenses of Turkey, future funding for Afghan forces and injecting "predictability" in NATO relations with an increasingly assertive Russia.

Stoltenberg said a decision on a formal invitation to Montenegro will come Wednesday, but two NATO diplomats said it's a done deal. Russia has warned Montenegro that its joining NATO would be regarded as a provocation.

NATO last expanded in 2009 when Albania and Croatia joined.