President Obama spoke with Russian President Vladimir Putin on Saturday, urging him to withdraw military forces from Ukraine and expressing "deep concern" over the situation.

The two leaders spoke for 90 minutes in an effort to defuse an international crisis in Ukraine, after Russia sent troops to secure a predominantly Russian region of the country.

Obama “expressed his deep concern over Russia’s clear violation of Ukrainian sovereignty and territorial integrity,” said the White House in a statement.

“The United States condemns Russia’s military intervention into Ukrainian territory,” the statement continued. “The United States calls on Russia to de-escalate tensions by withdrawing its forces back to bases in Crimea and to refrain from any interference elsewhere in Ukraine.”

The conversation came a day after Obama warned Russia publicly that there would be “costs” for military intervention and urged Russia to work with the international community to bring stability to Ukraine.

Ukraine is politically divided between a Western half that seeks closer ties with Europe and an eastern half with a large Russian population. Former Ukrainian President Viktor Yanukovych was removed from office after months of protests by opposition groups that rejected his push for closer trade ties with Moscow.

Yanukovych sought to end the protests with a brutal crackdown by his security forces that killed dozens. He fled the capital after the European Union brokered a peace deal that installed an interim government ahead of new elections.

Ukraine’s parliament removed Yanukovych from office and tapped a new president, but Yanukovych insists he is still in charge and has asked for Russia’s help.

Tensions escalated on Saturday after Russian lawmakers approved a request from Putin to send troops into Ukraine.

The White House said Obama told Putin that “if Russia has concerns about the treatment of ethnic Russian and minority populations in Ukraine, the appropriate way to address them is peacefully through direct engagement with the government of Ukraine and through the dispatch of international observers.”

“President Obama urged an immediate effort to initiate a dialogue between Russia and the Ukrainian government, with international facilitation, as appropriate,” said the White House, adding that the U.S. is “prepared to participate.”

Obama also warned of consequences for Moscow’s actions, making it “clear that Russia’s continued violation of Ukraine’s sovereignty and territorial integrity would negatively impact Russia’s standing in the international community,” the statement said.

“The United States will suspend upcoming participation in preparatory meetings for the G-8. Going forward, Russia’s continued violation of international law will lead to greater political and economic isolation,” the White House warned.

According to the Associated Press, top administration officials on Saturday met at the White House to discuss how the U.S. should respond to Russia's actions.

The report said the participants included CIA Director John Brennan, National Intelligence Director James Clapper, Joint Chiefs of Staff Chairman Gen. Martin Dempsey, and Defense Secretary Chuck Hagel.