President Donald Trump has signed off on the U.S. agreement of Montenegro joining the NATO military alliance.
Trump signed off on the instrument of ratification approved by the Senate last month in support of Montenegro joining the alliance.
This must be ratified by its 28 members.
The Balkan nation will attend the NATO leaders’ summit in Brussels next month, signalling to other NATO aspirants that the door to membership in the Euro-Atlantic community of nations remains open.
The U.S. would work to strengthen relations with the small Balkan nation, which would be the 29th NATO member.
The eastward expansion of the alliance has been a point of contention for Russia.
Two of the 28 NATO members, Spain and the Netherlands, have yet to ratify Montenegro’s membership.
NATO countries have pledged to spend 2 percent of their gross domestic product on defence. Only five, including the United States, currently meet that goal.
Trump during his presidential campaign called for member nations to increase defence spending to support the organization.
The treaty signing comes after the Senate on Mach 28 voted overwhelmingly to back Montenegro joining NATO.
Republican Senators Rand Paul (Ky.) and Mike Lee (Utah) were the only two Senate lawmakers to oppose the treaty.
Paul also blocked a vote on the treaty earlier in March, setting off Senate Armed Services Committee Chairman John McCain (R-Ariz.).
All current NATO members will also have to approve Montenegro's membership.
