U.S. intelligence officials say they believe pro-Russian rebels probably shot down the Malaysia airliner over eastern Ukraine "by mistake."
The officials say no direct link to Russia has been found.
U.S. intelligence officials said the passenger jet was likely downed by an SA-11 surface-to-air missile fire by the rebels.
While saying there was no link so far to the Kremlin, the officials said Russia had "created the conditions" for the downing of the plane.
They said they didn't know if any Russians were present at the missile launch, and they wouldn't say whether the missile crew was trained in Russia.
However, the officials added the Russian military has been training the rebels at a large base in Rostov on various weapons, including air defense systems.
But it was unclear if the Russians trained the separatists on the SA-11 missile batteries, officials said.
On July 21, President Barack Obama said the Malaysia Airlines plane with 298 onboard "was shot down over territory controlled by Russian-backed separatists in Ukraine."
He also said Russia has both trained the separatists and "armed them with military equipment and weapons, including anti-aircraft weapons."
The intelligence officials said they decided to brief reporters in Washington on July 22 in part to counter what they called "misinformation" from Russia and its state-controlled media over the incident, including allegations Ukraine may have been responsible itself for shooting down the jetliner.
The officials said it was unrealistic Kyiv had targeted the plane, since it had no missile launchers in the area.
For something like that to have happened, Ukrainian troops would have had to fight their way into the area, fire at the passenger plane and fight their way out again, the officials explained.
Moreover, the Ukrainian government would have had to orchestrate claims by separatists on social media that they had shot down a plane.
"That is not a plausible scenario to me," one official added.
Meanwhile, a team from Interpol has begun the process of identifying the victims of the plane crash.
A train bearing the dead reached Ukrainian-controlled territory on July 22, arriving at a factory in Kharkiv where Kyiv authorities have established their crash investigation center.
The crash killed all 298 people aboard the Boeing jumbo jet.
It's believed that the remains of about 200 victims were on the refrigerated train.
Most of the victims were from the Netherlands which will hold a day of mourning on July 23 as the country prepares for the arrival of the first bodies later in the afternoon.
At the crash site in the rebel-held east, reports said there was no sign of a full investigation.
International observers said there were signs that the debris was being mishandled or even tampered with.
Russian President Vladimir Putin said on July 22 that he would urge the separatists to allow a full investigation which the Netherlands said it would lead.
The black boxes, handed over by the rebels to Malaysia Airlines, will be transfered to British air accident investigators to be examined.
Meanwhile, EU foreign ministers meeting in Brussels on July 22 decided to widen "targeted measures" against Russia.
According to Reuters, EU foreign ministers for the first time raised the possibility of restricting Russian access to European capital markets, defence and energy technology.
British Foreign Secretary Philip Hammond said London wanted the measures to target friends and allies of Putin to pressure Russia to stop meddling in Ukraine.
EU envoys will discuss the wider target list for existing sanctions on July 24.
Based on reporting by AP and Reuters