Montenegro's Foreign Minister Igor Luksic, center, Montenegro's Defense Minister Milica Pejanovic-Durisic, left, and NATO Secretary General Jens Stoltenberg prepare to address the North Atlantic Council at NATO headquarters in Brussels on Wednesday, Dec. 2, 2015. NATO member states have formally invited the tiny Adriatic nation of Montenegro to join the alliance in the face of Russian opposition to the move. (John Thys, Pool Photo via AP)