President Obama says it is likely that a missile fired from rebel-held territory in eastern Ukraine brought down Malaysia Airlines MH17 and that at least one U.S. citizen is among the dead.
"Evidence indicates that the plane was shot down by a surface-to-air missile from an area controlled by Russian-backed separatists inside of Ukraine," Obama said, noting that it's not the only time in recent months that the pro-Russia rebels had taken down airplanes.
He called the deaths of the 298 people aboard the plane "an outrage of unspeakable proportions."
Obama referred to the arming of the rebels and the "steady flow of weapons from Russia" and said if Russian President Vladimir Putin makes a decision not to arm the separatists, then the flow will stop.
"There has to be a credible investigation," he said. "There must be an immediate cease-fire. Evidence must not be tampered with."
He promised U.S. assistance in the investigation.
All sides in the conflict in Ukraine — Kiev, the separatists, and Moscow — have denied any involvement in the downing of MH17.
Buk surface-to-air missile system