Obama, who earlier this week ramped up sanctions on Russia over the east Ukraine conflict between the Kiev government and pro-Russian sources, called on the country's president, Vladimir Putin, to "take the path that would result in peace in Ukraine".
Passengers' belongings at the crash site of Malaysia Airlines flight MH17 before a visit by Organisation for Security and Cooperation in Europe (OSCE) monitors, near the settlement of Grabovo in the Donetsk region. (Reuters photo)
"Evidence indicates that the plane was shot down by a surface-to-air missile that was launched from an area that is controlled by Russian-backed separatists inside of Ukraine," he said.
Read: World leaders call for Ukraine ceasefire after MH17 tragedy
Terming the MH17 crash a global tragedy, Obama said that at least one US citizen was among the 298 dead. The State Department identified the victim as Quinn Lucas Schansman, who also held Dutch nationality.
"Their (the passengers') deaths are an outrage of unspeakable proportions," Obama told reporters.
He stopped short of directly blaming Russia for the incident but warned that he was prepared to tighten economic sanctions. The US President echoed international calls for a rapid and credible investigation.
"Now is, I think, a somber, appropriate time for all of us to step back and take a hard look at what has happened. Violence and conflict inevitably lead to unforeseen consequences," Obama said.
Noting the global impact of the crash, with victims from 11 countries across four continents, he said the stakes were high for Europe, a clear call for it to follow the more robust sanctions on Russia already imposed by Washington.
Read: The crash of flight MH17 in Ukraine: a timeline
Meanwhile, Russia, whom Obama said was letting the rebels bring in weapons, said people should not prejudge the outcome of the inquiry.
Earlier in the day, the United States told the UN Security Council that Malaysia Airlines jet MH17 was "likely downed by an SA-11 missile, operated from a separatist-held location in eastern Ukraine".
A pro-Russian separatist holds a stuffed toy found at the crash site of Malaysia Airlines flight MH17, near the settlement of Grabovo in the Donetsk region.(Reuters photo)
US permanent representative to UN Samantha Power went on to say, "We cannot rule out Russian technical assistance" because of the technical complexity of SA-11.
Here are the details of US assessment of the shooting, as presented by Power at the US Security Council:
# The airliner was travelling at a cruise altitude of 33,000 feet and its speed was typical for an airliner along an established flight corridor frequented by commercial traffic. The flight was transmitting its assigned transponder code corresponding with its flight plan, and flight tracking data was publicly available on the internet. There was nothing threatening or provocative about MH17.
Read: Pro-Russian rebels admitted to downing Malaysia Airlines jet: Ukraine security service
# Of the operational SAM systems located near the border, only the SA-11, SA-20, and SA-22 SAM systems are capable of hitting an aircraft at this flight's altitude of 33,000 feet. We can rule out shorter-range SAMs known to be in separatist hands, including MANPADS, SA-8 and SA-13 systems, which are not capable of hitting an aircraft at this altitude. Early Thursday, an SA-11 SAM system was reported near Snizhne by a Western reporter and separatists were spotted hours before the incident with an SA-11 system at a location close to the site where the plane came down.
# Separatists initially claimed responsibility for shooting down a military transport plane and posted videos that are now being connected to the Malaysian airlines crash. Separatist leaders also boasted on social media about shooting down a plane, but later deleted these messages. Because of the technical complexity of the SA-11, it is unlikely that the separatists could effectively operate the system without assistance from knowledgeable personnel. Thus we cannot rule out technical assistance from Russian personnel in operating the systems.
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# The Ukrainians do have SA-11 systems in their inventory. However, we are not aware of any Ukrainian SAM systems in the area of the shoot down. And, more importantly, since the beginning of this crisis, Ukrainian air defenses have not fired a single missile, despite several alleged violations of their airspace by Russian aircraft.
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# This also follows a pattern of actions by Russian-backed separatists. On June 13, separatists shot down a Ukrainian transport plane, carrying 40 paratroopers and nine crew. On June 24, as this Council was meeting to welcome Ukraine's unilateral ceasefire, we received word that separatists downed a Ukrainian helicopter, killing all nine on board.
# On July 14, separatists claimed credit for the downing of a Ukrainian military cargo plane, flying at 6,000 meters, and on July 16, they claimed credit for the downing of a Ukrainian fighter jet.
(With agency inputs)
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