Obama Says US Is Considering Steps to Isolate Russia as Putin Refuses to Pull Back Forces in Ukraine

President Barack Obama condemned Russia's military intervention in Ukraine, saying on Monday that the United States is considering diplomatic and economic steps "that will isolate Russia."

Russia is on "the wrong side of history," Obama told reporters from the White House as he denounced the country for violating Ukraine's sovereignty and territorial integrity and international law.

"There a violation of previous agreements that Russia has made with respect to how it treats and respects its neighbors, and as a consequence we got strong statements from NATO, from the G7, condemning the actions that Russia has taken," he stated.

The standoff over Russia's military intervention in Ukraine's Crimean Peninsula remained Monday with Russia vowing not to pull back its troops despite warnings by world leaders that Moscow's defiance will involve "significant costs."

Russia's Foreign Minister Sergei Lavrov, who was in Geneva Monday, said that Russian troops will remain in Ukraine "until the normalization of the political situation."

"The victors intend to make use of the fruits of their victory to attack human rights and fundamental freedoms of minorities," BBC quoted Lavrov as saying. He claimed "violence of ultra-nationalists threatens the lives and the regional interests of Russians and the Russian speaking population."

British Foreign Secretary William Hague, who was in Kiev Monday, called the turmoil the "biggest crisis" to face Europe in the 21st Century, and also indicated that Russia's G8 membership could be at risk. Echoing Obama, the British official warned Moscow of "significant costs."

"It is a very tense and dangerous situation that Russia's intervention has now produced," Hague told BBC Radio. "The world cannot just allow this to happen. The world cannot just say it is OK, in effect, to violate the sovereignty of another nation in this way."

Foreign ministers of the European Union are meeting in an emergency session in Brussels Monday, even as the Organization for Security and Cooperation in Europe is also meeting and has sent two observers to Crimea, according to The New York Times. The United States is also expected to send monitors to Ukraine under the flag of either the United Nations or the security organization.

Ethnic Russian forces, who seized Crimea without any violence over the weekend, made attempts to disarm the small Ukrainian contingents there Sunday, Reuters reported. Crimea is an isolated Black Sea peninsula with a majority Russian population where Moscow has a naval base.

Ukraine's acting president, Oleksandr Turchynov, has ordered Ukrainian troops to be placed on high combat alert.

Turchynov was appointed acting president after pro-Russia Viktor Yanukovych was removed by Ukraine's parliament last week. More than 82 people were killed in three months of anti-government protests that began following Yanukovych administration's suspension of preparations for signing an Association Agreement and a Free Trade Agreement with the European Union, in favor of closer economic relations with Russia.

Ukraine's foreign minister, Andriy Deshchytsya, met European and U.S. officials Saturday and requested NATO to "examine all possibilities to protect the territorial integrity and sovereignty of Ukraine."

U.S. Secretary of State John Kerry late Saturday condemned "the Russian Federation's invasion and occupation of Ukrainian territory."

Putin on Saturday won approval of the parliament to intervene "in connection with the extraordinary situation in Ukraine, the threat to the lives of citizens of the Russian Federation, our compatriots" as well as to protect the Black Sea Fleet in Crimea.

The parliamentary approval came a day after Obama warned Russia, saying any military intervention in Ukraine will be "deeply destabilizing" and involve "costs."

"We are now deeply concerned by reports of military movements taken by the Russian Federation inside Ukraine," Obama said at the White House Friday. "It would be a clear violation of Russia's commitment to respect the independence and sovereignty and borders of Ukraine and of international laws … Any violation of Ukraine's sovereignty and territorial integrity would be deeply destabilizing, which is not in the interest of Ukraine, Russia or Europe."