(Dimitar Dilkoff/AFP/Getty Images | Alexey Nikolsky/AFP/Getty Images | Ron Sachs-Pool/Getty Images)

By Mary Bruce, Jonathan Karl and Ali Weinberg

It was quite a split-screen moment: As Secretary of State John Kerry was still speaking in Kiev today, President Obama ridiculed Russian President Vladimir Putin's justification for intervention in Ukraine's Crimean peninsula and warned that he is violating international law.

"I know President Putin seems to have a different set of lawyers making a different set of interpretations, but I don't think that's fooling anybody," the president said at an event in Washington, D.C., when asked about Putin's defiant comments today defending his right to use force if necessary to protect ethnic Russians in Ukraine.

"We stand on the side of history that I think more and more people around the world deeply believe in - the principle that a sovereign people, an independent people are able to make their own decisions about their own lives," Obama said.

"And you know, Mr. Putin can throw a lot of words out there, but the facts on the ground indicate that right now he's not abiding by that principle," the president added. "There is still the opportunity for Russia to do so, working with the international community to help stabilize the situation. And we've sent a clear message that we are prepared to work with anybody if their genuine interest is making sure that Ukraine is able to govern itself."

The styles were quite different: Kerry firmly denouncing Russia actions; Obama much more measured, referring to reports Putin is considering a "pause" for the moment.

But the message was the same: Both Kerry and Obama taking issue with Putin's claim that he is defending Russians facing persecution in Ukraine.

Speaking in Kiev, Kerry used far more pointed language, accusing Putin of spreading fabricated rumors in order to justify military aggression in the Ukrainian region of Crimea, and perhaps even elsewhere in the country.

He also praised the new Ukrainian transitional government, which took the place of ousted president Viktor Yanukovich, for showing "restraint" in the face of Russian aggression and intimidation.

"The contrast really could not be clearer: determined Ukrainians demonstrating strength through unity, and the Russian government out of excuses, hiding its hand behind falsehoods, intimidation and provocations," Kerry said, speaking at a press availability shortly after meeting with key members of the transitional government in the country's parliament.

"There is nothing strong about what Russia is doing," he continued, saying their assertions of Ukrainian aggression, the illegitimacy of the transitional government and threats to Russian military bases in Crimea were simply Putin's attempts to create a "pretext" for being able to invade further into the country.

Kerry warned, as he and other United States officials have in recent days, of a united international front against Russia if it does not withdraw its troops from Crimea.

"Our partners will have absolutely no choice but to join us to continue to expand upon steps we have taken in recent days in order to isolate Russia politically, diplomatically and economically," he said.

Kerry spoke with emotion about walking through a street in Kiev where 67 protesters were killed on Feb. 20, when violence between the Ukrainian opposition and Yanukovich government reached a fever pitch.

"It was very moving and it gave me a deep personal sense of how closely linked the people of Ukraine are to not just Americans but to people all across the world who today are asking for their rights, asking for the privilege to be able to live, defining their own nation, defining their futures."