President Obama Calls For Pro-Russian Separatists To Stop Tampering With MH17 Crash Site

    "What exactly are they trying to hide?"

    Four days after the downing of Malaysia Airlines Flight MH17 in Ukraine, President Obama says the Russian-backed separatists continue to block international investigators from the crash site.

    "What exactly are they trying to hide?" the president asked, speaking from the White House on Monday.

    President Obama urged Russian President Vladimir Putin to compel the pro-Russian rebels to stop tampering with and grant access to investigators at the MH17 crash site. "We know that Russia has trained them, armed them, and key leaders are Russian citizens," Obama said. "The burden now is on Russia."

    Obama called for a diplomatic solution to the situation in Ukraine, but suggested that if President Putin did not cooperate with the international community, "costs will increase" for Russia.

    Ukraine President Petro Poroshenko told CNN's Cristiane Amanpour Monday that 16 bodies are still missing from the crash. The rest are in a refrigerator train but still blocked by separatists.

    "The world deserves to know exactly what happened," Obama said.