Russian President Vladimir Putin says his country is prepared to use all options to protect Russians in Ukraine, but that he hopes it will not have to use force.
President Putin's comments Tuesday come amid a growing crisis over Russia's military presence in the Ukrainian region of Crimea. The United States and its European allies are considering sanctions against Russia for its troop movements into Ukraine.
Mr. Putin said those considering sanctions should consider the damage they, too, will suffer from the measures.
In his first public comments since ousted Ukrainian President Viktor Yanukovych fled Kyiv, the Russian leader called Ukraine's political power shift an unconstitutional "coup" and said Mr. Yanukovych is still Ukraine's "legitimate" leader, though he has "no political future."
U.S. Secretary of State John Kerry is due in Kyiv Tuesday, where he will meet members of the interim government and reinforce U.S. support for Ukraine's sovereignty.
As Kerry was on his way to the Ukrainian capital, Mr. Putin ordered tens of thousands of troops taking part in military exercises in western Russia, near the Ukrainian border, to return to base. The exercises were scheduled to end, so it is unclear whether the move was intended to help ease tensions.
Moscow has denied that the exercises, started last week, were related to the situation in Ukraine.
On Monday night, U.S. President Barack Obama met with Kerry, Defense Secretary Chuck Hagel and other members of his national security team at the White House to discuss policy options.
Earlier Monday, President Obama called on Congress to approve an aid package for the new Ukrainian government.
In tandem with the diplomatic push, the U.S. Defense Department said Monday it is suspending military-to-military contacts with Russia. Pentagon spokesman Rear Admiral John Kirby said the move is aimed at prodding Moscow to de-escalate the Ukraine crisis, and said the suspension covers maneuvers, bilateral meetings, port visits and conference planning.
European Union foreign ministers have issued a Thursday deadline for Russian President Vladimir Putin to pull back his troops or face punitive measures.
Russia, meanwhile, is calling on Ukraine to return to a February 21 agreement between ousted President Viktor Yanukovych and the opposition that involved forming a national unity government.
But State Department spokeswoman Psaki said Monday that while the agreement could be used as a "basis," the dramatic change in circumstances since then means it is not usable as it is.
President Obama accused Russia Monday of violating international law with its actions in Ukraine. He said the country is "on the wrong side of history."
Russia says its military movements in Ukraine are to protect its citizens there. But the U.S. ambassador to the United Nations, Samantha Power, told an emergency session of the U.N. Security Council Monday that Russia's intervention is an "act of aggression," and not the humanitarian mission it is seeking to portray.
U.S. Vice President Joe Biden spoke Monday by telephone with Russian Prime Minister Dmitry Medvedev. The White House said Biden urged Russia to withdraw its forces from Ukraine, support the immediate deployment of international monitors and begin a "meaningful political dialogue" with the Ukrainian government.
Crimea is a Black Sea peninsula placed under Ukrainian control in 1954 by then-Soviet leader Nikita Khrushchev. It remained part of Ukraine when the Soviet Union collapsed in 1991. Crimea has a tiny border with Russia on its far eastern point, and the Crimean port of Sevastapol is home to Russia's Black Sea fleet. Most of the people living in Crimea are ethnic Russians, but the region also is home to ethnic Muslim Tatars, who generally show disdain for Russia.
Ukraine's troubles began in November, when President Yanukovych backed out of a trade deal with the European Union in favor of closer ties and economic aid from Russia. The move triggered weeks of pro-Western anti-government demonstrations in Kyiv and elsewhere in Ukraine, and forced the pro-Russian Yanukovych to flee the capital in late February.