United States President Donald Trump pushes his way to the front of the world stage in Brussels on Thursday, shoving aside the leader of the soon-to-be member Montenegro at a NATO summit.

Video showing the leaders caught Trump pushing his way past Prime Minister Dusko Markovic, then confidently adjusting his suit as he emerged in the front of the group, closer to NATO head Jens Stoltenberg.

Video of the incident went viral and came as Trump delivered a tough message to NATO allies to dramatically increase their defence spending to ease financial burden to the United States.

The NATO mission of Montenegro, which is joining the Western military alliance against stiff opposition from Russia, did not immediately respond to a request for comment.