- The United States believes pro-Russian rebels shot down the Malaysia Air jetliner
- American officials say Russia bears the blame for supplying rebels with missiles
- A U.S. official said Russia 'will have a hard time explaining this away'
- But it's unclear how Russia's Vladimir Putin will respond. Will he back down in Ukraine?
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.
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."
That means "we cannot rule out technical assistance from Russian personnel in operating the systems," she added.
Officials said regardless of whether Russian operatives were manning the system, Russia bears responsibility for the attack because of its military and political support for the rebels.
In recent weeks, Russia has intensified its delivery of sophisticated military equipment, officials said.
"While it may take us some time to firmly establish who shot down a plane filled with innocents, most (U.N. Security Council) members and most members of the international community have been warning for months about the devastation that would come if Russia did not stop what it started, if it did not rein in what it unleashed," Power said.
Another senior U.S. official said that the "responsibility is Russia's whether they had Russian personnel there or they gave them equipment and an instruction manual" on what to do.
"These separatist leaders are taking orders from Russia 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.
The same official said that over the past 24 hours, Moscow has played "the usual game of deflection," noting it has put out "nonsense stories to send people down a rabbit hole" and hamper the investigation.
"It's not going to work," the official said. "The outrage is too deep and the evidence, including videos of separatists bragging about this, is too damning. They will have a hard time explaining this away."
President Barack Obama warned that without a stop in support to the rebels, Putin would face more international sanctions.
The administration this week escalated sanctions on key business sectors of the Russian economy over Ukraine.
Putin and the Russian government "have to make a strategic decision," Obama said on Friday. "Are they going to continue to support violent separatists whose intent is to undermine the government of Ukraine? Or are they prepared to work with the government of Ukraine to arrive at a cease fire and a peace that takes into account the interests of all Ukrainians?"
U.S. officials said it was unclear whether the incident could be a turning point in Russia's support for the rebels, but stressed a tough message would be sent to Putin once the final determination is made about what happened regarding Malaysia Air Flight 17.
How will Putin respond ultimately, especially on personnel and weapons sent to Ukraine?
"If he ever had an intention of backing off, this could be an opportunity for him to do that," another U.S. official said. "I don't think he does have that intention, though."
Officials noted, however, the tragedy would likely close any gap between the United States and the European Union over how severe the international response should be toward Russia.
"This is very likely to harden views that Russia is not a problem," one official said. "If there were any Europeans who believe it had nothing to do with them, that Ukraine was merely a local issue, that will change."