April 11 (UPI) -- President Donald Trump on Tuesday signed the U.S. instrument of ratification for Montenegro to become the 29th member of NATO.
Only the Netherlands and Spain remain to complete the procedure of verification for entry into the NATO alliance, which was formed in 1949.
In a letter to Orrin Hatch, the Senate president pro tempore, Trump wrote, "the inclusion of Montenegro in the North Atlantic Treaty Organization (NATO) will not have the effect of increasing the overall percentage share of the United States in the common budgets of NATO; and the inclusion of Montenegro in NATO does not detract from the ability of the United States to meet or to fund its military requirements outside the North Atlantic area."
Montenegro became a sovereign state in a referendum in May 2006, breaking away from Serbia, which was part of the former Yugoslavia.
Trump plans to attend the NATO leaders meeting in Brussels on May 25.
"Montenegro will be there as well, signaling to other NATO aspirants that the door to membership in the Euro-Atlantic community of nations remains open and that countries in the Western Balkans are free to choose their own future and select their own partners without outside interference or intimidation," the White House said in a statement. "The United States will work to further strengthen our already strong relationship with Montenegro and looks forward to formally welcoming the country as the twenty-ninth member of the NATO Alliance."
For seven years, Montenegro has applied for NATO membership.
In NATO's Article 5, members agree to defend any NATO country threatened by force.
Lee said before the Senate vote: "I don't see how the accession of Montenegro, a country with the population smaller than most congressional districts and a military smaller than the police force of the District of Columbia, is beneficial enough that we should share an agreement for collective defense."
Montenegro is bordered by Croatia, Bosnia, Herzegovina, Serbia, Kosovo, Albania and the Adriatic Sea. It has a current estimated population of 626,217, according to Worldometers.