Obama arrives in Europe with a warning for Putin

By Kevin Liptak, CNN White House Producer

As Air Force One landed in Estonia's capital Wednesday, the U.S. message to Vladimir Putin -- only 500 miles away in Moscow -- was clear: Stay put.

President Barack Obama's trip to the former Soviet state, ahead of this week's NATO summit in Wales, is meant to reassure nervous Eastern Europe that Putin's support for separatists in Ukraine doesn't mean he has a free pass for territorial gains elsewhere.

The warning to Russia was summed up by a top Obama foreign policy adviser last week: "Don't even think about messing around in Estonia or in any of the Baltic areas in the same way that you have been messing around in Ukraine."

Added to the schedule only last month, the stop in Estonia will supplement the message coming from NATO leaders gathering in Cardiff, Wales, who are set to announce the positioning of troops and equipment closer to Russia in Eastern Europe.

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Speaking alongside Estonia's President, Obama recalled the "deep ties" between the two nations as he announced plans for additional U.S. Air Force units to be based in Estonia as part of a bolstering of NATO forces in the region.

"One of our goals at the summit over the next several days is to once again project unity across NATO on behalf of Ukraine's efforts to maintain its sovereignty and territorial integrity," Obama said.

He added that Russia was "paying a heavy price for its actions," in part through Western sanctions imposed over Ukraine, and that NATO is poised to do more to help Ukraine defend itself.

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The NATO leaders also must confront the separate threat of militant Islamists making gains in Syria and Iraq, and the brutal beheading of a second American by ISIS, also known as ISIL or the "Islamic State."

Asked about his strategy on the extremist group, Obama said: "The bottom line is this: Our objective is clear, and that is to degrade and destroy ISIL so it's no longer a threat not just to Iraq, but also to the region and to the United States.

"In order for us to accomplish that, the first phase has been to make sure we've got an Iraqi government that's in place, and that we are blunting the momentum that ISIL was carrying out.

"And the airstrikes have done that. But now, what we need to do is make sure that we've got the regional strategy in place that can support an ongoing effort, not just in the air, but on the ground, to move that forward."