BRUSSELS (AP) — Montenegro's flag has been raised at NATO headquarters in Brussels after the Balkans country officially became the 29th member of the world's biggest military alliance this week.

NATO Secretary-General Jens Stoltenberg called it a historic day. He said Wednesday that Montenegro now has a seat at NATO's table and an equal voice in the decisions the alliance makes.

NATO's decisions are made by consensus instead of majority vote, giving each country a potential veto.

Montenegro President Filip Vujanovic said membership would guarantee his country "a stable, secure and prosperous" future.

Despite opposition from Russia, Montenegro joined NATO on Monday after completing its membership formalities in Washington.

Its Balkans neighbors Albania and Croatia were the last countries to join NATO, in 2009.