Evidence was growing on Sunday that Malaysian Airlines flight MH17 was shot down by a missile fired from the vicinity of two neighbouring towns near the crash site within rebel-controlled eastern Ukraine.
Analysis of videos and photos posted on social media sites on the day the plane was brought down show a mobile Buk anti-aircraft missile launcher in the town of Torez, about six miles south of the farmland where the wreckage is scattered, and then in Snizhne, two miles east of Torez. Washington said that one of its satellites had detected a missile launch from the vicinity of those towns at the time the Boeing 777 was brought down.
Eliot Higgins, a video and photographic analyst, published the pictures on his investigative journalism website Bellingcat. "The guy who uploaded one of the videos, deleted the video and his accounts a few hours after the plane came down," Higgins said.
"There is a cluster of two videos and two photos we have analysed that show a Buk missile-launcher in Torez, at about midday from the angle of the sun, and then about an hour and half later in Snizhne."
Higgins said that the pictures were not clear enough to be sure whether the mobile launcher in Snizhne was the same as the one in Torez.
The Ukrainian interior ministry also released a short video that appeared to show a Buk launcher with at least one missile missing being transported along a road on a trailer, claiming the weapon was being driven across the border into Russia.
The video analysis confirms an earlier Associated Press report that one of its journalists spotted a Buk-like launcher in an area of eastern Ukrainian controlled by separatists, contradicting claims by rebel leaders not to have such missiles.
The Buk, known to the US military as an SA-11 Gadfly, can reach targets up to altitudes of 46,000 feet. MH17 was flying at 33,000 feet en route from Amsterdam to Kuala Lumpur.
Both the Ukrainian and Russian armed forces possess the launchers, which work alongside a separate mobile radar and a command vehicle. Experts say its target-acquisition technology is good enough to spot aircraft, but not to differentiate between civilian and military planes.
The US state department on Sunday published its most detailed version of the attack on the Malaysian airliner. "At the time that flight MH17 dropped out of contact, we detected a surface-to-air missile launch from a separatist-controlled area in southeastern Ukraine.
"We believe this missile was an SA-11," a statement from the US embassy in Kiev said, adding that the launch was in the area of Torez and Snizhne.
"Intercepts of separatist communications posted on YouTube by the Ukrainian government indicate the separatists were in possession of a SA-11 system as early as Monday July 14th. In the intercepts, the separatists made repeated references to having and repositioning Buk (SA-11) systems."
The embassy statement also said that US intelligence audio analysts believed the intercepts of rebel commanders discussing the shooting down of the plane were genuine.
It claimed that over the weekend of 12-13 July Russia sent a convoy of military equipment with up to 150 vehicles, including tanks, armoured personnel carriers artillery, and multiple rocket launchers to the separatists. The statement also said Russia was training separatist fighters in south-west Russia, including on anti-aircraft systems.
Vitaly Nayda, Ukraine's counterintelligence chief, said that Buk missile launchers were seen crossing into Russia from eastern Ukraine on Friday morning.
A definitive investigation was still being prevented on Sunday by eastern separatist groups imposing access restrictions. The rebels were removing bodies and the Ukrainian government accused them of sanitising the scene of evidence.
A team of six investigators from Britain's Air Accidents Investigation Branch was sent to Ukraine soon after the disaster to take part in an international enquiry, but a spokeswoman from the AAIB said: "They are still in Kiev, while the format for an investigation is being established." She declined to go into further detail but it is believed that the investigators have not gone to the crash site, east of Donetsk, for lack of security assurances.
Senior figures in the air accident investigation community have said that the crash site is becoming increasingly contaminated, hindering the chances of a full independent inquiry.
Phil Giles, formerly with the AAIB, said: "It's absolutely crucial to seal of any crash site because it's similar to the scene of a crime and you don't want any contamination. The reason the site needs not to be disturbed is because if you accidentally shot down a Malaysian Airlines plane, the first you would do is find the record casing [from the aircraft] and disappear it."