Obama to Reassure Allies, Send Warning to Putin

President Barack Obama began a three-day European tour Wednesday with a stop in Estonia, a NATO ally which borders Ukraine.

The president's trip is aimed at reassuring the Baltic states that the U.S. will defend them if Russia threatens more incursions.

"I've come here first and foremost to re-affirm the commitment of the United States to the security of Estonia," Obama said. "That is a commitment that is unbreakable, it is unwavering, it is eternal."

Russia's military activities in Ukraine have Estonia and other NATO allies in the region concerned.

They fear if Putin succeeds in taking chunks of Ukraine, he might go after them next.
    
One U.S. official said Obama's visit is aimed at telling Russian President Vladimir Putin, "Don't even think about messing around here."     
    
The NATO summit begins Thursday in Wales.