“We are now deeply concerned by reports of military movements taken by the Russian Federation inside of Ukraine,” said the president in a statement from the White House briefing room.
“Just days after the world came to Russia for the Olympic Games, it would invite the condemnation of nations around the world and indeed the United States will stand with the international community in affirming that there will be costs for any military intervention in Ukraine,” he added.
The president’s remarks came after Kiev accused Moscow of an “armed invasion” and said Russian troops had seized control of airports in Crimea, a region of Ukraine.
The troop movements came amid fears that Russia will seek to destabilize Ukraine’s caretaker government or reassert influence over its neighbor.
Obama said there was a peaceful role to play by Moscow in helping bring political stability to Ukraine, but said Kiev must control its own destiny.
“We have been very clear about one fundamental principle, the Ukrainian people deserve the opportunity to determine their own future. Together with our European allies we have urged an end to the violence and encouraged Ukrainians to pursue a course in which they stabilize their country and forge a broad based government and move to elections this spring,” said Obama.
Obama said that he had spoken several days ago with Russian President Vladimir Putin and that his officials were in “daily” contact with their Moscow counterparts.
“We have made clear that they can be part of an international community’s effort to support the stability and success of a united Ukraine going forward,” said Obama.
Former Ukrainian President Viktor Yanukovych, who was backed by Moscow, fled the capital city after a brutal crackdown by his security forces on opposition groups failed to end months of protests.
The European Union brokered a peace deal to end the political violence, install a caretaker government and set a timetable for new elections. Kiev’s parliament voted to remove Yanukovych from office and named a new interim president.
Yanukovych, though, insists he is the legitimate leader of Ukraine and has asked Russia to protect him.
Moscow has also ordered military exercises near the border, raising fears, it will intervene with force.
Ukraine is politically divided between a Western half that seeks closer ties with Europe and an eastern half with a large Russian population.
The president acknowledged that Russia has a “historic relationship with Ukraine” but he cautioned that “any violation of Ukraine’s sovereignty and territorial integrity would be deeply destabilizing which is not in the interests of Ukraine, Russia or Europe.”
“It would represent a profound interference with in matters that must be determined by the Ukrainian people. It would be a clear violation of Russia’s commitment to respect the independence and sovereignty and borders of Ukraine and of international law,” he added.
Obama added that the situation was “very fluid” and said Vice President Joe Biden had spoken with Ukraine’s prime minister to assure him “in this difficult moment that the United States supports his government’s efforts and stands for the sovereignty and territorial integrity and democratic future of Ukraine.”
The president also commended Kiev’s “restraint” in handling the situation.
Ambassador to the United Nations Samantha Power said earlier Friday that the U.S. “stands with the Ukrainian people.”
She said the administration was “gravely disturbed” by the movement of Russian troops into Ukraine and called on Russia to pull back those forces.
This story was published at 5:19 p.m. and has been updated.