President Obama declared Monday that "the burden is now on Russia" to demand open and unfettered access to the crash site of the downed Malaysia Airlines passenger jet from eastern Ukrainian militants.
"Given its direct influence over the separatists, Russia and President Putin in particular have a direct responsibility to compel them to cooperate with the investigation," Obama said.
"All of which begs the question, what exactly are they trying to hide?" Obama said.
The president called the obstruction "an insult to those who have lost loved ones" and "the kind of behavior that has no place in the community of nations."
The comments came hours after a late-night statement released by the Kremlin in which Putin said other countries should not use the plane's downing “to pursue their own political goals.”
"Rather than dividing us, tragedies of this sort should bring people together,” he said.
Putin also called for access for the United Nations' International Civil Aviation Organization to survey the crash site.
“We must do everything possible to ensure their complete and guaranteed safety and provide them with the humanitarian corridors they need for their work,” Putin said. “For its part, Russia will do everything within its power to move the conflict in eastern Ukraine from the military phase we see today to the negotiating phase, with the parties using peaceful and diplomatic means alone.”
Obama said he appreciated Putin's words but added that the call needed to be backed up by concrete efforts to influence the separatists.
"Now is the time for President Putin and Russia to pivot away from the strategy they've taken," Obama said.
The United Nations Security Council is expected to vote on a resolution on Monday demanding open access to the site.
Obama ignored shouted questions from reporters about whether the United States would look to impose sanctions on Russia over the plane downing, either unilaterally or in concert with European allies.
Europe's foreign ministers will meet on Tuesday to discuss the possibility of additional sanctions, and leaders from the U.K., France and Germany have been discussing their response.
In a press release, Downing Street said the EU “should be ready to impose further sanctions,” if Putin did not act to open access to the site.
“What we need to do now is use the sense of shock, the sense of outrage, to galvanize opinion behind a more robust stance,” Philip Hammond, the U.K. foreign secretary, told the BBC.