Updated

The Malaysian Airline flight that crashed in eastern Ukraine was likely brought down by a SA-11 surface-to-air missile from anti-central government forces in that part of the country, the U.S. Embassy in the capital city of Kiev said Sunday.

Embassy officials said they based their analysis on several factors including the increasing flow in recent months of heavy weapons from across the Russian border to the so-called “separatist fighters.”

Russia took control of the Ukraine city of Crimea shortly after citizens this winter ousted pro-Russian President Viktor Yanukovych. And since then, the separatists, who appear to have strong military backing from Russia, have battled in eastern Ukraine against new central-government forces.

The embassy officials said that Russia last weekend sent a convoy of military equipment with up to 150 vehicles including tanks, armored personnel carriers, artillery and rocket launchers to the separatists They also said they have information indicating the separatists are being trained at a facility in southwest Russia on air-defense systems.

The pro-Russian separatist fighters, officials said, also have “demonstrated proficiency with surface-to-air missile systems and have downed more than a dozen aircraft over the past few months, including two large transport aircraft.”

The assessment is essentially identical to the one that Secretary of State John Kerry gave Sunday while making his rounds on the morning talk shows.

Russian President Vladimir Putin said Friday that Ukraine was responsible for the downing of the passenger plane because the country's central government had renewed its military campaign against the separatists.

Embassy officials also said they detected a surface-to-air missile launch from a separatist-controlled area in southeastern Ukraine at the same time contact was lost Thursday with flight MH17. They also think the missile was a SA-11.

All 298 people on board the commercial flight were killed.

The officials also said communications posted on YouTube and intercepted by the Ukrainian government indicate the separatists were as recently as Wednesday in possession of a SA-11 system.

In addition, social media postings on Thursday purportedly show a SA-11 system being moved through the separatist-controlled towns of Torez and Snizhne, near the crash site.

“From this location, the SA-11 has the range and altitude capability to have shot down flight MH17,” said the embassy, adding that video posted on social media this weekend shows an SA-11 headed toward Russia on a transporter and that the system appeared to be missing at least one missile.

Officials made clear Ukraine also has such systems but were “confident” none was within range of the crash.

Ukrainian forces have also not fired a single surface-to-air missile during the conflict, they said.

The release also contained other published assessments including separatists, among them self-proclaimed “Defense Minister” of the Donetsk People’s Republic Igor Strelkov, claiming on a call and on social media responsibility for shooting down a military transport plane.