Ukraine Puts Forces on 'Highest' Combat Alert as Russia Moves In 3r War World.

Kerry Condemns Russian Action in Ukraine as 'Invasion'

US President, Barack Obama, has spoken on the phone to Russian President, Vladimir Putin, to discuss rising tensions in Ukraine. Obama reportedly raised serious concerns over any possible intervention by the Russian military. Putin said Russia reserves the right to protect its interests in the region as well as the safety of ethnic Russians in Ukraine.

Pro-Russian protesters with Russian flags take part in a rally in central Donetsk March 1, 2014. The banner reads, "In Russia, we have brothers, In Europe, we are slaves."

U.S. 'Suspends' Role in Russia G8 Summit After Obama, Putin Speak

The U.S. is preparing to pull out of the next summit of industrialized nations — scheduled in Russia — in protest of Russian military moves in Ukraine, the White House said Saturday after President Barack Obama and Russian President Vladimir Putin spoke directly by phone.

Obama told Putin in the 90-minute call that he was deeply concerned over Russia's "clear violation of Ukrainian sovereignty and territorial integrity," the White House said in a statement, adding that the president warned Putin that Russia's "standing in the international community" was at stake.

Sen. John McCain of Arizona, a member of the Armed Forces Committee and a leading Republican spokesman on foreign policy, urged Obama to take an even harder line

after the upper house of Russia's parliament gave Putin the power to use military force.

"Every moment that the United States and our allies fail to respond sends the signal to President Putin that he can be even more ambitious and aggressive in his military intervention in Ukraine," McCain said.

But just because Putin was granted new powers to use military force doesn't mean he will do so any time soon, Russian Deputy Foreign Minister Grigory Karasin said.In what might have been an attempt to put a velvet glove on an iron fist, Karasin said Putin's power may not be activated quickly.

He gave no time frame for military action, and diplomats said it was possible that the announcement was intended more to send a message to international powers that Russia wouldn't back down over the future of Ukraine.