"The adoption of fundamental acts affecting the key issues of state security thorough the vote of individual lawmakers on the basis of formal majority and without taking into account the public opinion is a blatant act of trampling all democratic norms and principles," the ministry said in a statement.
"Given the potential of Montenegro, the North Atlantic Alliance is unlikely to receive significant "added value". But Moscow can not ignore the strategic consequences of this step. Therefore, we reserve the right to adopt decisions that are aimed at protecting our interests and national security," the statement said.
In May 2016, the alliance members signed a protocol on Montenegro's accession to be ratified by all NATO member states before becoming a full-fledged member.
On April 25, US President Donald Trump signed the protocol on Montenegro’s accession to NATO, which was the final step in ratifying the document.