NATO foreign ministers have agreed to invite Montenegro to join the military alliance. The move is likely to lead to further deterioration in NATO’s relations with Russia, which sees the alliance’s expansion eastward as a threat to its national security.

“We congratulate Montenegro,” NATO Secretary-General Jens Stoltenberg told the meeting at the alliance headquarters in Brussels.

“This is the beginning of a very beautiful alliance,” he added.

Montenegro’s parliament voted in September for a resolution to support the country’s accession to NATO. The resolution was passed by 50 votes out of 79, with the opposition calling for a national referendum on the issue.

The intention by Prime Minister Milo Djukanovic’s government to make Montenegro part of NATO was one of the reasons for violent mass protests in the capital Podgorica in October, when thousands of people rallied in front of the parliament building to demand his resignation.

Djukanovic, who has been in power for two decades – both before and after Montenegro became independent from Serbia – was also accused of corruption, and of being responsible for the country’s poor economic performance and rising crime rate.