The United States assessed that Flight MH17 was likely downed by a SA-11 surface-to-air missile from separatist-controlled territory in eastern Ukraine. This judgment is based on several factors. Over the past month, there was detected an increasing amount of heavy weaponry to separatist fighters crossing the border from Russia into Ukraine, IPN reports.

According to an assessment by the U.S. Government, disseminated by the U.S. Embassy, Russia recently sent a convoy of military equipment with up to 150 vehicles including tanks, armored personnel carriers, artillery, and multiple rocket launchers to the separatist. The U.S. also has information indicating that Russia is providing training to separatist fighters at a facility in southwest Russia, and this effort included training on air defense systems.

Pro-Russian separatist fighters 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. At the time that flight MH17 dropped out of contact, the U.S. detected a surface-to-air missile (SAM) launch from a separatist-controlled area in southeastern Ukraine. We believe this missile was an SA-11.

Ukraine also operates SA-11 systems, but the U.S. is confident no Ukrainian air defense systems were within range of the crash. Ukrainian forces have also not fired a single surface-to-air missile during the conflict, despite often complaining about violations of their airspace by Russian military aircraft.

Shortly after the crash, separatists – including the self-proclaimed “Defense Minister” of the Donetsk People’s Republic Igor Strelkov – claimed responsibility for shooting down a military transport plane on social media. In an intercepted conversation that has been widely posted on the internet, a known-separatist leader tells another person that a separatist faction downed the aircraft. 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) SAM system.

The United States says the video posted on social media yesterday show an SA-11 on a transporter traveling through the Krasnodon are back to Russia. The video indicated the system was missing at least one missile, suggesting it had conducted a launch. Events on the ground at the crash site clearly demonstrate that separatists are in full control of the area

A plane flying from Amsterdam to Kuala Lumpur was downed last week. All passengers on board, mainly Dutch citizens, died.