Montenegro's membership in the NATO alliance was formalized on Monday, ending a two-year long process marked by tension with Russia and an attempted coup against the former Soviet satellite state.

"We are an ally that will enjoy the benefits provided by the collective system of security with major responsibility to continue together with you unwaveringly and committedly to work towards durable peace, stability, and security of Europe and the world," Montenegrin Prime Minister Dusko Markovic said through a translator at the State Department. "This is a task that will be passed on to the next generations."

Montenegro's accession to the alliance, taking place against the backdrop of President Trump's victory in the 2016 elections and renewed Russian aggression in Ukraine, acquired more symbolic value than the small Balkan country's military power would carry. Russia opposed the treaty vehemently, while many American lawmakers wanted to signal U.S. willingness to commitment to the region.

"Over decades, the promise of NATO membership and broader Euro-Atlantic integration has advanced our security, our democratic values, and our respect for the rule of law," Tom Shannon, the number-three official at the State Department, said at the accession ceremony. "It has served as an incentive for nations to pursue difficult reforms. This policy has yielded clear results, and that is why NATO allies unanimously agreed to welcome Montenegro into the alliance."

The Senate vote in favor of allying with Montenegro nearly was unanimous, but still produced fireworks on the floor. Sen. Rand Paul, a libertarian-leaning Republican from Kentucky, repeatedly blocked a vote on the issue, angering some of his colleagues — who said he did so without elaborating on his reasons.

"That is really remarkable," Senate Armed Services chairman John McCain said in March. "That a senator, blocking a treaty that is supported by the overwhelming number, perhaps 98 at least of his colleagues, would come to the floor and object, and walk away . . . The senator from Kentucky is now working for [Russian President] Vladimir Putin."

Paul was equally forceful in his retort. "I think he makes a really, really strong case for term limits," he said on MSNBC. "I think maybe he's past his prime; I think maybe he's gotten a little bit unhinged.

Paul also suggested that the wWst should be skeptical of allowing former Soviet states into the alliance, particularly in light of Russia's annexation of Crimea and the ongoing violence in eastern Ukraine. "I think having former satellites or former parts of the Soviet Union is NATO is very provocative," he said. "And so the 45 soldiers that Montenegro has I think are hardly an asset to our national security. And, really, our decisions need to be about our national security. And so I just don't think it enhances our national security to have Montenegro part of NATO."

Montenegro has about 2,000 soldiers, but it also controls the only ports on the Adriatic Sea otherwise beyond NATO control. Russia, historically a close partner of Montenegro, will not have access to those ports. That contributed to the bipartisan consensus in favor of the treaty.

"While a small country, Montenegro's NATO membership will help the western alliance protect a vital coastline in the Adriatic and continue the process of bringing peace, democracy, and stability to the Balkans," New York Rep. Eliot Engel, the top Democrat on the Foreign Affairs Committee said in January. "It is also a strong bipartisan endorsement of the continued vitality of the NATO alliance and the collective security it guarantees in Europe."

Montenegro accused Russia of supporting a failed coup attempt designed to overthrow the parliament and prevent NATO membership. "Behind these events are nationalist structures from Russia, but we now know that certain Russian state authorities were involved also on a certain level," a state prosecutor said in February.

Putin's spokesman denied the allegations — "We do not interfere in the internal affairs of other countries," he said — but Moscow has put other forms of pressure on Montenegro. On the economic front, the Russian government banned the importation of wine from the Adriatic nation just days before the parliament voted to join NATO.

"Taking into account Montenegro's potential, the North Atlantic Alliance is unlikely to have a considerable ‘added value,'" the Russian Foreign Ministry said in April. "But Moscow cannot but take into account strategic consequences of this step. That is why we reserve the right to take such decisions which are aimed at the protection of our interests and national security."