Speaking live on Ukrainian TV, Turchynov said he had also ordered stepped up security at nuclear power plants, airports and other strategic infrastructure.
Ignoring President Barack Obama's warning Friday that "there will be costs" if Russia intervenes militarily, Putin sharply raised the stakes in the conflict over Ukraine's future evoking memories of Cold War brinkmanship.
After Russia's parliament approved Putin's motion, U.S. officials held a high-level meeting at the White House to review Russia's military moves in Ukraine. The White House said President Barack Obama spoke with Putin by telephone for 90 minutes and expressed his "deep concern" about "Russia's clear violation of Ukrainian sovereignty and territorial integrity."
The White House said Obama told Putin that the United States is calling on Russia "to de-escalate tensions by withdrawing its forces back to bases in Crimea and to refrain from any interference elsewhere in Ukraine."
A statement from the Kremlin said Putin emphasized to Obama the existence of "real threats" to the life and health of Russian citizens and compatriots who are in Ukrainian territory. The statement indicated that Russia might send its troops not only to the Crimea but also to predominantly ethnic Russian regions of eastern Ukraine.
"Vladimir Putin emphasized that, in the case of a further spread in violence in eastern regions (of Ukraine) and Crimea, Russia maintains the right to protect its interests and the Russian-speaking population that lives there," the Kremlin statement said.
Obama told Putin that he would support sending international monitors to Ukraine to help protect ethnic Russians. He said the U.S. will suspend its participation in preparatory meetings for June's G-8 summit in Sochi, Russia, the site of the recently concluded Winter Olympics, warning that Russia's "continued violation of international law will lead to greater political and economic isolation."
NATO announced a meeting for Sunday of the North Atlantic Council, the alliance's political decision-making body, as well as a meeting of the NATO-Ukraine Commission. NATO secretary general Anders Fogh Rasmussen said the allies will "coordinate closely" on the situation in Ukraine, which he termed "grave."
The U.N. Security Council met in an open, televised session for about a half hour on Saturday afternoon after closed-door consultations, despite initial objections from Russia to an open session. The council heard speeches from a U.N. deputy secretary-general and several ambassadors, but did not take any action.
Ukraine's Ambassador to the U.N. Yuriy Sergeyev asked the Security Council "to do everything possible now" to stop what he called Russian "aggression." Russia's U.N. ambassador, Vitaly Churkin, said the government in Kiev needs to get away from "radicals" and warned, "such actions they're taking could lead to very difficult developments, which the Russian Federation is trying to avoid." He said Russia was intervening at the request of pro-Russian authorities in the autonomous Crimea region that is part of Ukraine.
Calling the situation in Ukraine "as dangerous as it is destabilizing," U.S. Ambassador to the U.N. Samantha Power said, "It is time for the Russian military intervention in Ukraine to end." She warned that "Russia's provocative actions could easily push the situation beyond the breaking point." She asked that Russia directly engage the Ukraine government and called for international monitors to be sent to Ukraine to observe the situation.
"Russia and the West find themselves on the brink of a confrontation far worse than in 2008 over Georgia," Dmitri Trenin, the director of Carnegie Moscow Center, said in a commentary posted on its website. In Georgia, Russian troops quickly routed the Georgian military after they tried to regain control over the separatist province of South Ossetia that has close ties with Moscow.
The latest moves followed days of scripted, bloodless turmoil on the peninsula, the scene of centuries of wars and seen by Moscow as a crown jewel of the Russian and Soviet empires. What began Thursday with the early-morning takeover of the regional parliament building by mysterious troops continued Saturday afternoon as dozens of those soldiers — almost certainly Russian — moved into the streets around the parliamentary complex and seized control of regional airports, amid street protests by pro-Russian Crimeans calling for Moscow's protection from the new government in Kiev.
That government came to power last week in the wake of months of pro-democracy protests against the now-fugitive president, Viktor Yanukovych, and his decision to turn Ukraine toward Russia, its longtime patron, instead of the European Union. Despite the calls for Moscow's help, there has been no sign of ethnic Russians facing attacks in Crimea or elsewhere in Ukraine.
Obama on Friday called on Russia to respect the independence and territory of Ukraine and not try to take advantage of its neighbor's political upheaval.