BRUSSELS (AP) — Russia takes center-stage at NATO Tuesday as allied foreign ministers meet to debate ways to dissuade Moscow from destabilizing Ukraine and encourage it to respect a landmark Cold-war era nuclear treaty.

U.S. Secretary of State Mike Pompeo and his NATO partners will hold talks with Ukrainian Foreign Minister Pavlo Klimkin as Kiev seeks international support for its Black Sea confrontation with Russia.

Russian border guards fired on three Ukrainian navy vessels in the Black Sea near the Russia-occupied Crimea on Nov. 25. The vessels and the crews were captured.

But it is unclear what more NATO would do beyond the sea patrols and air policing it already does in the region.

Noting that Ukraine isn't a member of the alliance, NATO Secretary-General Jens Stoltenberg said the allies already "provide strong political support and strong practical support."

NATO allies have helped modernize Ukraine's armed forces and boosted their presence in the Black Sea over the last year, with more ships deployed in the region and more air policing. Three NATO allies on the Black Sea — Bulgaria, Romania and Turkey — are also taking individual measures.

NATO nations, individually and through the European Union, have also imposed economic and other sanctions on Russia since it annexed Ukraine's Crimean Peninsula in 2014, but there is little appetite among the allies to broaden those measures.

In any case, Russia remains defiant. Despite NATO launching its biggest military buildup in Europe since the Cold War, Russia's actions near the Sea of Azov last weekend demonstrate that the increased allied presence won't deter its aims in eastern Ukraine.

Of similar concern to NATO is Russia's new SSC8 missile system. The U.S. has shared intelligence evidence with its allies that the ground-fired cruise missile could give Moscow the ability to launch a nuclear strike in Europe with little or no notice.

Washington says the system contravenes the 1987 Intermediate-range Nuclear Forces Treaty, which bans all land-based cruise missiles with a range between 500 and 5,500 kilometers (310-3,410 miles), and President Donald Trump is threatening to pull out of the bilateral pact.

"It's urgent that Russia ensures full compliance in a transparent and verifiable way, because the INF treaty is so important for our security," Stoltenberg told reporters Tuesday.

Some European allies suspect that Trump could give notice in coming months that the U.S. is leaving the treaty. That would give Russia a notice period of six months to decide whether to comply.