The signing ceremony, attended by Montenegrin Prime Minister Milo Djukanovic, took place at the ongoing two-day North Atlantic Council (NAC) session at the alliance’s headquarters in Brussels.
"We intend to carry on with reforms, especially in the area of the rule of law. We need to continue striving toward good results in the areas of fighting organized crime and corruption, we need to secure the support of the majority of the population for Montenegro's NATO membership, we will also carry on with reforms on the defense sector," Djukanovic said ahead of the signing ceremony.
Montenegro will be granted membership to the alliance once the protocol is ratified by all 28 NATO member states.
"We expect Montenegro to pursue its reforms. This work remains important. And NATO will continue to provide support and assistance. It will give Montenegro a seat at the table and the ability to shape NATO policy," Stoltenberg said, noting progress achieved by reforms up to date.
On December 2, 2015, NATO invited Montenegro to join the military bloc, in its first expansion into Eastern Europe in six years. Podgorica accepted the invitation the following day, which triggered protests in the Balkan nation. On Wednesday, Montenegro's Democratic Front party leader Milan Knezevic said that more than half of the country's citizens were opposed to their country joining NATO.