Russian forces massed along Ukraine's eastern border could threaten stability in a separatist region of neighboring Moldova, the American general who serves as NATO's top military commander said Sunday.
"The force that is at the Ukrainian border now to the east is very, very sizable and very, very ready," Air Force General Philip Breedlove said at a meeting of the German Marshall Fund think-tank in Brussels.
Breedlove added that Russia clearly had anticipated and prepared for action in Crimea for some time. "Russia tried to get a local face in Crimea with local militias, but there was a thin veneer of locals in the front and a lot of men in green behind," he said, referring to Russian troops in unmarked uniforms.
The comments drew a quick response from Moscow, where Russian Deputy Defense Minister Anatoly Antonov dismissed concerns about the buildup of troops. He told the news agency Tass and other media outlets that Russia was "in compliance" with all international agreements on limits of troops in regions bordering Ukraine.
Russia's ambassador to the European Union, Vladimir Chizhov, told the BBC that Russia had no intention of sending troops into other parts of Ukraine or Europe. He defended Russia's actions in Crimea as solely an effort protect ethnic Russians in the region.
The Transdniestria region of Moldova declared itself independent in 1990, although no countries in the United Nations recognize it. It's population of about 500,000 people is about one-third ethnic Russian, and some members of its parliament have urged Russia to annex the region.
Meanwhile, a Ukrainian air force commander was being held after his base in Crimea was stormed by pro-Russian forces, and Ukraine's acting president called for his release.
Col. Yuliy Mamchur led the Belbek Air Force base near Sevastopol, which was taken over Saturday by forces who sent armored personnel carriers smashing through the base's walls and fired shots and stun grenades. One Ukrainian serviceman was reported wounded in the clash. It was unclear whether the forces, who didn't bear insignia, were Russian military or local pro-Russia militia.
President Oleksandr Turchyno said Mamchur was "abducted." Vitali Klitschko, head of Ukraine's Democratic Alliance for Reform, said Sunday that Mamchur is being held by the Russian military in a jail in Sevastopol, the Crimean city that is the base of Russia's Black Sea Fleet.
Klitschko was one of the leaders of the three months of protests in Ukraine that culminated in late February with President Viktor Yanukovych fleeing the country and interim authorities taking power before a May 25 presidential election. That fueled Russia's push to take control of Crimea.
Russia formally annexed Crimea last week, a move that Western countries say is illegitimate. The U.S. and the EU have imposed sanctions on Russia in the dispute.
Contributing: Associated Press