SIMFEROPOL, March 31 - Prime Minister Dmitry Medvedev flaunted Russia's grip on Crimea by flying to the region and holding a government meeting there on Monday, angering Ukraine and defying Western demands to hand the peninsula back to Kiev.

But in a gesture that could ease tension in the worst East-West standoff since the Cold War, Russia pulled some troops back from near Ukraine's eastern frontier - a move the United States said would be a positive sign if it is confirmed as a withdrawal.

At the Kadamovsky training ground, a Reuters reporter saw hundreds of troops pile into over 40 armored personnel carriers and a long line of military trucks. The convoy then headed off from the area, which lies in the Rostov border region.

President Vladimir Putin told German Chancellor Angela Merkel that he had ordered a partial drawdown in the region, Merkel's spokesman said.

But Medvedev's visit taunted Western leaders by underlining their inability to force Putin to relinquish Crimea, seized after the overthrow of Russian-backed Ukrainian President Viktor Yanukovych and formally annexed on March 21.

Accompanying Medvedev, outspoken Deputy Prime Minister Dmitry Rogozin, who has been targeted by Western sanctions, left no doubt about the symbolism of the trip, saying on Twitter: "Crimea is ours. Basta!"

The Ukrainian government denounced the visit as a "crude violation" of the rules of diplomacy, a few hours after the latest round of crisis talks between Russia and the United States ended inconclusively.

Western countries have expressed concern about a Russian troop buildup on the Ukraine border.

But the Russian Defense Ministry said a battalion from the central military district's 15th motorized infantry brigade was pulling back to its home base of Samara on the Volga River after what it called month-long exercises.

In Washington, the White House reacted cautiously to the troop movements. "We've seen the reports and if they are true and if - more importantly - they represent further withdrawals, that would be a positive sign," said spokesman Jay Carney. "It is certainly something that we have explicitly called for."

Putin and Merkel also discussed by phone ways of stabilizing Ukraine and another former Soviet republic, Moldova. A Kremlin statement quoted Putin as calling for a comprehensive solution that would end what he called a "blockade" of Moldova's breakaway region of Transdniestria.

NATO foreign ministers meet in Brussels on Tuesday to examine steps to reinforce Eastern European countries worried by Russia's annexation of Crimea.

Diplomats said the ministers from the 28-member alliance would look at options ranging from stepped-up military exercises and sending more forces to Eastern member states, to the permanent basing of alliance forces there - a step Moscow would view as provocative.

The NATO ministers, in a meeting with Ukrainian Foreign Minister Andriy Deshchytsia, are also expected to offer help to make Ukraine's armed forces more efficient.

Ukraine sent a protest note to Moscow over Medvedev's trip, declaring that an official visit to its territory without its consent "is a crude violation of the rules of the international community." (rt/ez)