While the administration had previously not taken any public position on the matter, Secretary of State Rex Tillerson has reportedly written a letter to the Senate urging their ratification of Montenegro's bid to join NATO as its newest member.
The tiny Adriatic nation of Montenegro was granted a Membership Action Plan in December 2009, and was formally invited into NATO in December 2015. Polls have shown Montenegrin voters split roughly down the middle on the question of member, though the government generally supports it. Tillerson argues it is "strongly in the interests of the United States" for Montenegro to join.
The Senate overwhelmingly supports to move too, though Sen. Rand Paul (R – KY), as the lone opponent is making the vote difficult, with Sen. John McCain (R – AZ) last week accusing Paul of working for Vladimir Putin for blocking his attempt at a unanimous consent action on Montenegro.