Update: In a brief statement, Obama told reporters that he was "deeply concerned" over reports of Russian military movement in Ukraine. He added that "there will be costs for any intervention in Ukraine." 

Noting that the U.S. had invited Russia to "be part" of an international effort to address the situation in Ukraine, Obama cautioned the Moscow government against taking unilateral action. The president reminded Russia that the country just hosted representatives from all over the world at the Sochi Olympics, noting that further military action by the country could result in "international condemnation." 

Obama also "commended the Ukrainian government's restraint" in the face of the developing situation there. 

Original post: In minutes, President Obama will deliver a late Friday statement on the developing situation in Ukraine. Watch here: 

Earlier on Friday, armed men seized control of two airports in the Russia-friendly Ukrainian region of Crimea. Although there are still conflicting reports on the origin of those men, the U.S. now reportedly believes that there are some Russian troops on the ground in the region. 

The president's statement follows a warning from acting Ukrainian President Oleksandr Turchynov that Russia should stop "provocations" in Ukraine. And earlier on Friday, Secretary of State John Kerry issued a stern warning to Russia over the Moscow government's intentions in Ukraine. 

Update, 6:03 p.m. Here's the full text of the President's statement, via this document

Over the last several days, the United States has been responding to events as they unfold in Ukraine.  Throughout this crisis, 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, forge a broad-based government and move to elections this spring.

I also spoke several days ago with President Putin, and my administration has been in daily communication with Russian officials, and we've 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, which is not only in the interest of The people of Ukraine and the international community, but also in Russia’s interest.

However, we are now deeply concerned by reports of military movements taken by the Russian Federation inside of Ukraine.

Russia has a historic relationship with Ukraine, including cultural and economic ties, and a military facility in Crimea, but any violation of Ukraine’s sovereignty and territorial integrity would be deeply destabilizing, which is not in the interest of Ukraine, Russia, or Europe.

It would represent a profound interference in matters that must be determined by the Ukrainian people.  It would be a clear violence of Russia’s commitment to respect the independence and sovereignty and borders of Ukraine, and of international laws.  And 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 events of the past several months remind us of how difficult democracy can be in a country with deep divisions.  But the Ukrainian people have also reminded us that human beings have a universal right to determine their own future.

Right now, the situation remains very fluid.  Vice President Biden just spoke with Prime Minister -- 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.  I also commend the Ukrainian government’s restraint and its commitment to uphold its international obligations.

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.

Thanks very much.