Lithuania expects NATO to reach an agreement next year to shield Baltic countries with air defenses, plugging a gap in its security against Russia, its defense minister said Tuesday.

Since Russia annexed the Crimea peninsula from Ukraine in 2014 and began providing weapons and troops to separatist rebels in eastern Ukraine, NATO has sent more forces to the Baltics, eastern Poland and around the Black Sea.

Lithuania, which borders the Russian region of Kaliningrad, wants NATO to permanently deploy anti-aircraft weapons in the Baltics or Poland — a move seen by Moscow as an unjustified military buildup on its borders.

"We expect so," Defense Minister Raimundas Karoblis told Reuters when asked if he saw an agreement shaping up for the NATO summit in 2018. "Air defense is one of the issues which we need to address. We also need to look at other domains, like NATO command structure reform, we need to move forward on all on these aspects," he said, also calling for NATO to strengthen maritime defenses in the Baltics.

Karoblis spoke in Helsinki after meeting his counterparts from Northern Group countries, including the Nordic and Baltic states, Britain, Germany, Poland and the Netherlands. U.S. Secretary of Defense Jim Mattis also joined the meeting.

Karoblis said exercises should be considered by NATO after Russia's Zapad war games unnerved the West in September.

Mattis told reporters after the meeting that the 12 nations stood together to reaffirm territorial integrity.

"It is clear that one nation thinks it holds some kind of a veto or strong influence over others, that is Russia. The country's name came up repeatedly over the last 48 hours," he said.