Obama asserted that America's interest was in seeing the Ukrainian people be able to determine their own destiny.
"My interest is seeing the Ukrainian people be able to determine their own destiny," Obama told White House reporters in a joint press availability with visiting Israeli Prime Minister Benjamin Netanyahu. "Russia has strong historic ties to the Ukraine. There are strong commercial ties between those two countries.
And so all of those interests I think can be recognised. But what cannot be done is for Russia, with impunity, to put its soldiers on the ground and violate basic principles that are recognised around the world," he said.
Asserting that the US and its global partners were supportive of the interim Ukrainian government, Obama said "the strong condemnation that it has received from countries around the world indicates the degree to which Russia is on the wrong side of history on this."
Obama: Russia has strong historic ties to the Ukraine
Secretary of State John Kerry will be travelling to Kiev to indicate the US support for the Ukrainian people, to offer very specific and concrete packages of economic aid - because one of the things the US concerned about is stabilising the economy even in the midst of this crisis, he said.
"What we are also indicating to the Russians is that if, in fact, they continue on the current trajectory that they're on, that we are examining a whole series of steps - economic, diplomatic - that will isolate Russia and will have a negative impact on Russia's economy and its status," he said.
"We've already suspended preparations for the G8 summit. I think you can expect that there would be further follow-up on that. We are taking a look a whole range of issues that John Kerry mentioned yesterday," Obama said.