BELGRADE – Montenegro and NATO will sign an accession agreement on May 19, paving the way for the Balkan country to become the 29th member of the military alliance.

Montenegrin Prime Minister Milo Djukanovic will be in Brussels to sign during a two-day meeting of NATO foreign ministers.

“It is an historic day for the alliance, for Montenegro and for the stability of the Western Balkans,” NATO Secretary-General Jens Stoltenberg said. “The enlargement of NATO with Montenegro confirms that NATO’s door is open.”

Montenegro would be the third nation from the Western Balkans to join NATO after Albania and Croatia.

After signing, Montenegro, once part of Yugoslavia, will participate in the alliance’s meetings as an observer until all NATO nations ratify its accession protocol.

Stoltenberg said there is “strong support” in NATO for Montenegro’s membership, despite threats from Russia to respond to the move. Moscow views NATO’s move increasingly closer to its border as a threat.

“Any sanctions or reactions from Russia will be absolutely unjustified,” Stoltenberg said. “It’s a sovereign decision of a sovereign nation, Montenegro, to decide on its own path, and that should be respected by everyone.”