Washington (CNN) -- The United States predicts the shooting down of Malaysia Airlines Flight 17, likely by pro-Russian rebels, will fundamentally shift the relationship between Russia and the international community. "It is a game-changer," one senior State Department official said. While Washington has stopped short of blaming Russia, U.S. Ambassador to the United Nations Samantha Power said Friday the United States believes the jet carrying nearly 300 people was downed by a surface-to-air missile fired by pro-Russian rebels in eastern Ukraine. U.S.: Russia may have helped operate system Due to the sophistication of the Buk missile system believed to have been used, Power said it was "unlikely that the separatists could effectively operate the system without assistance from knowledgeable personnel."
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The United States believes pro-Russian rebels shot down the Malaysia Air jetliner
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American officials say Russia bears the blame for supplying rebels with missiles
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A U.S. official said Russia 'will have a hard time explaining this away'
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But it's unclear how Russia's Vladimir Putin will respond. Will he back down in Ukraine?
Officials said regardless of whether @placeholder operatives were manning the system, Russia bears responsibility for the attack because of its military and political support for the rebels.
"These separatist leaders are taking orders from @placeholder and (Russian President Vladimir Putin) has to realize the consequence of sending heavy and sophisticated weapons to a gang of sociopaths, extremists, violent thugs, nationalists and agents who are just given weapons and told to make chaos," the official said.
Or are they prepared to work with the government of @placeholder to arrive at a cease fire and a peace that takes into account the interests of all Ukrainians?"