President Donald Trump on Tuesday approved the addition of Montenegro to NATO, a move that’s likely to anger Russia, which opposes the expansion of the alliance.

The move comes after Trump dismissed NATO as “obsolete” on the campaign trail.

The White House press office released a statement praising NATO and affirming US commitment to strengthening its “already strong relationship with Montenegro.”

“Since its inception in 1949, the NATO Alliance has been central to ensuring peace and security on the European continent,” the White House said in the statement. “It is an alliance not only of shared interests but of shared values. President Trump looks forward to the May 25 NATO Leaders Meeting in Brussels and the opportunity to reaffirm those fundamental and enduring transatlantic values.”

The statement also contained a veiled reference to Russian opposition to Montenegro’s inclusion in NATO, saying it wil signal “to other NATO aspirants that the door to membership in the Euro-Atlantic community of nations remains open” and that countries in that region are free to “select their own partners without outside interference or intimidation.”

At the end of March, the Senate also voted in approval of Montenegro’s inclusion in NATO, 97 to 2. And 21 of 28 NATO allies have already backed Montenegro’s membership. Before Montenegro officially joins NATO, the rest of the alliance’s member countries need to ratify the decision.

While the Senate was considering Montenegro’s NATO membership, Sen. John McCain, a Republican from Arizona, explained the importance of standing in defiance of Russian aggression around the former Soviet Union’s sphere of influence.

“It is a nation in this contest that we are now engaged in with Vladimir Putin, who has committed to extending the reach and influence of the Russian government … to the point where he attempted a coup to overthrow the freely elected government of Montenegro,” McCain said. “If we turn down Montenegro, it will not remain the democracy that it is today.”

Russian President Vladimir Putin staunchly opposes Montenegro’s accession to NATO, which he views as a threat to Russian sovereignty. Albania and Croatia joined the alliance 2009.

Russian intelligence agents allegedly orchestrated a coup plot to overthrow Montenegro’s pro-NATO government and replace it with a Russia-friendly regime, The New York Times reported last year.

Despite criticisms that the Trump administration is too close to Russia, the president and his secretary of state have stood by Montenegro in its bid for NATO membership.

Secretary of State Rex Tillerson wrote to Senate leaders last month saying it is “strongly in the interests of the United States” to approve Montenegro’s inclusion in NATO.

This is the second time in recent weeks that the Trump administration has made moves that could anger Russia.

Last week, Trump ordered a strike on military infrastructure belonging to the regime of Syrian President Bashar al-Assad, a close ally of Russia.

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