WASHINGTON — President Donald Trump has signed off on Montenegro's upcoming accession into NATO, helping pave the way for the military alliance's expansion in the Balkans.

The White House says in a statement that Trump looks forward to welcoming Montenegro as the 29th member of the NATO alliance at next month's meeting in Brussels.

The Senate in March voted overwhelmingly to ratify the tiny Balkan nation's entry into the alliance.

Russia strongly opposes the expansion of the Western military alliance in a region it considers part of its strategic sphere of interest.

Trump's move comes ahead of his White House meeting on Wednesday with NATO Secretary General Jens Stoltenberg.