US officials stop short of blaming crash directly on Moscow and say separatists likely shot down plane by accident

US intelligence officials accused Moscow of "creating the conditions" that resulted in the death of 298 people aboard the Malaysian Airlines jet shot down last week over a part of Ukraine controlled by Russia-backed separatists.

But in a partial declassification of US intelligence on Tuesday, officials stopped short of laying the blame for the disaster directly at the door of Russia. The assessment of the US intelligence community is that the separatists shot the plane down by accident.

The newly declassified information largely reaffirmed an account given last Friday by Samantha Power, US ambassador to the United Nations, saying that a missile from an SA-11 anti-aircraft battery in separatist territory shot down the plane.

Officials said training given by Russia to its separatist proxies on air-defense weapons, which they have used in recent weeks to shoot down about a dozen aircraft, was a contributing factor. Ukrainian forces fighting the separatists have yet to fire a surface-to-air missile, intelligence officials said, as their conflict is on the ground.

Facebook Twitter Pinterest MH17 shootdown graphic from US intelligence report on the downing of the Malaysian airliner in Ukraine. Photograph: US intelligence community

Some of the evidence provided by US intelligence – whose fiscal 2013 budget was $68bn – included Facebook posts. "After it became evident that the plane was a civilian airliner, separatists deleted social media posts boasting about shooting down a plane and possessing a Buk (SA-11) surface-to-air missile system," a senior intelligence official said in the briefing, held on condition of anonymity. The Guardian was not invited to the briefing, a transcription of which was later made available.

Despite enormous international opprobrium placed on Moscow since the crash, intelligence officials said that they believed Russia continues to arm the separatists. They alleged that rocket launchers, other artillery pieces and tanks have transited through a "training facility" in south-west Russia associated with supplies for the separatists.

While the Guardian cannot independently confirm the allegation, satellite imagery released by US intelligence and dated Monday from the Rostov base seems to depict columns of materiel not present in a photo dated a month earlier.

Images of Russian training facility near Ukraine border, from a US intelligence report on the downing of MH17. Photograph: US intelligence community

An account by US intelligence of the Buk missile's trajectory puts its origin at the town of Snizhne, not far from the Russian border. Images posted on social media from Snizhne seem to depict a mobile Buk system.

A still from the 'social media overview' section of a US intelligence report into the downing of MH17. Photograph: US intelligence community

An investigation into the destruction of MH17 has barely got under way. Separatists handed over the flight recorder of the plane to Malaysian authorities late on Monday.

US intelligence officials indicated that their timed release of preliminary information was designed to counter claims from the Russian military they consider obfuscatory.

"We are seeing a full-court press by the Russian government to instruct affiliated or friendly elements to manipulate the media," an intelligence official said.

On Tuesday, international experts began the process of identifying the bodies of those who died in the disaster, after a train carrying their remains arrived in the Ukrainian city of Kharkiv.

Interpol, the international police agency, said one of its teams had begun preliminary identification work on the remains, which will all be flown to the Netherlands this week for fuller identification.

The train, which included three refrigerated wagons, had been loaded by rebels and local emergency workers at Torez station, near the crash site. The rebels said there were 282 bodies and 87 "other fragments" on board and that 16 bodies are yet to be found.

However, on Tuesday night Dutch officials said only 200 bodies had arrived in Kharkiv.

The European Union said on Tuesday that it would expand its sanctions blacklist to target Vladimir Putin's inner circle and draw up further broad measures including an arms embargo and financial restrictions on Russian businesses.

• This article was amended on 23 July 2014 because an earlier version said two images of a Russian training facility were taken two days apart. This has been corrected to say a month apart.