President Barack Obama bluntly warned Russia on Friday that it will face international condemnation as well as unspecified "costs" for any military intervention in neighboring Ukraine. A senior U.S. official said Washington could boycott a major international summit to be hosted by Russia in June and reject Moscow's efforts to promote trade with the United States.

"We are now deeply concerned by reports of military movements taken by the Russian Federation inside of Ukraine," Obama said in a hastily arranged public 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," the president warned.

His remarks came after top Ukrainian officials charged that Russian troops had taken over the two main airports in the strategic Crimean peninsula.

[Related: Ukrainian official says 8 Russian cargo planes in Crimea]

The president did not confirm Moscow's apparent role in the deployments, but he declared that "any violation of Ukraine's sovereignty and territorial integrity" would be "deeply destabilizing" and amount to a "profound interference" in its neighbors' affairs, as well as a violation of international laws.

"Throughout this crisis, we have been very clear about one fundamental principle: The Ukrainian people deserve the opportunity to determine their own future," he said.

"Right now, the situation remains very fluid," Obama said. "Vice President Biden just spoke with the prime minister of Ukraine to assure him that in this difficult moment, the United States supports his government's efforts and stands for the sovereignty, territorial integrity and democratic future of Ukraine.

"We will continue to coordinate closely with our European allies, we will continue to communicate directly with the Russian government, and we will continue to keep all of you in the press corps and the American people informed as events develop," he said.

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Obama's remarks were the latest sign that the crisis over Ukraine, where protesters and the parliament pushed pro-Moscow President Viktor Yanukovych from power, will not end quietly or anytime soon. Top U.S. officials have reached out to their Russian counterparts in recent days, including Obama calling Russian President Vladimir Putin.

Hours before Obama's surprise statement, Secretary of State John Kerry said he had discussed the situation with Russian Foreign Minister Sergey Lavrov.

"I asked specifically that Russia work with the United States and with our friends and allies in order to support Ukraine, to rebuild unity, security, and a healthy economy," Kerry said. Lavrov "reaffirmed President Putin’s statement that Russia will respect the territorial integrity of Ukraine," Kerry said.

It was unclear what sort of action Obama might take or what limited approach would deter the Russians.

The United States is consulting with its European allies on next steps, a senior administration official told Yahoo News. One option: Boycott the Group of Eight summit due to be held in June in the Black Sea resort of Sochi. Another option: Reject Russian efforts to promote trade with the United States. Putin sent a team of officials to Washington this week for just that purpose.

And Russia will face other possible costs, such as a worsening of its already shaky international reputation, and a drop in the value of its currency, the ruble, making imports more expensive and reducing the relative value of its exports.