President Obama said Friday that he'll be talking to key European leaders as he travels in South Korea to make sure the Europeans share his assessment that Russia has not lived up to promises made last week to de-escalate tension in Ukraine.
Mr. Obama said it's important to lay the groundwork for stronger sanctions, so that "if and when we see even greater escalation, perhaps even a military incursion by Russia into Ukraine, that we're prepared for the sort of sectoral sanctions that would have even larger consequences."
The president emphasized that European leaders have been "unequivocal in condemning Russia," but that coordination on stronger sanctions is not a simple or speedy process.
"They have a whole process that they've got to go through to deal with any actions that have significant impact on their own economies," he said, "and so there's some variation inside of Europe, that is as much of an issue as it is any differences between our assessments and theirs."
So far Washington has been trying to raise the costs for Russia while leaving the door open for de-escalation, Mr. Obama said, but the United States will "continue to keep some arrows in our quiver."
Still, Mr. Obama conceded, stronger sanctions may not change Russian President Vladimir Putin's calculus.
"There are no guarantees in life, generally, and certainly no guarantees in foreign policy," he said.
The president spoke at a joint press conference with South Korea's President Park Geun-hye, during Mr. Obama's four-nation Asia trip.
The president also addressed nuclear tests in North Korea.
The president said it's important to look at ways to apply more pressure on North Korea, including "further sanctions that have even more bite."
He also said that when combined with a "thoroughly irresponsible foreign policy," North Korea's missile technology and nuclear program "poses a threat to the United States."