A hunt for wreckage and evidence is underway in eastern Ukraine Friday after a Malaysia Airlines jetliner with 298 passengers was shot down.
U.S. intelligence authorities said a surface-to-air missile brought down Malaysia Airlines Flight 17 Thursday as it flew from Amsterdam to Kuala Lumpur, but could not say who fired it.
The Ukraine government in Kiev, the separatist pro-Russia rebels they are fighting and the Russia government that Ukraine accuses of supporting the rebels all deny shooting the passenger plane down. Moscow also denies backing the rebels.
Bodies, debris and burning wreckage of the Boeing 777 were strewn over a field near the rebel-held village of Hrabove in the Donetsk region of eastern Ukraine, about 40 kilometers (25 miles) from the Russian border, where fighting has raged for months.
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Get the latest updates and expert analysis about the crash in the WTOP live blog.
Philip Ewing - Politico senior defense reporter
Defense Sec. Chuck Hagel has been briefed. Defense officials "are staying well clear of attributing a cause to this crash."
"Given the history of U.S. support for Ukraine and the new Ukrainian government that there could well be a role for the Defense Department down the line."
Sophisticated air defense systems can hit planes at that altitude or even higher. These systems include large vehicles that support a missile the size of a telephone pole or larger. Administration officials believe "there are a lot of Russian heavy weapons moving into the border with Ukraine."
But whether those weapons are inside Ukraine or in Russia is unclear.
On President Obama:
"He does not want to have World War III with Russia in these eastern portions of Ukraine. It's going to be a very difficult tightrope to walk going forward if in fact this does turn out to be a shoot down or some other military cause for this crash. "
Anton Fedyashin - American University history professor in Moscow
"The reaction is actually very restrained."
"The version here is that no one knows exactly who is responsible. The Russian news ... is talking about either side being potentially at fault."
"So far the only sources that we have heard from and that the Russian news media have picked up is the pro-federalization forces in Eastern Ukraine offering to work with the international committee that investigates such accidents."
JJ Green - WTOP national security correspondent
Intelligence and security sources have serious concerns about two planes shot down in the region during the past few days including a Ukrainian fighter jet and a transport plane.
The rebel forces in Ukraine are skilled and organized and are believed to be either part of the Russian military or are at least supported by the Russian military, And they have stolen at least one missile launcher since the spring.
"They certainly have the capability of shooting down a plane at altitude."
What happens next? In the short term, airlines will be urged to avoid flying over this region of Ukraine and to avoid travelling to the conflict region. In the long term, it will be debated whether passenger plans should be equipped with defensive equipment, like flares, that can deter or deflect heat-seeking missiles.
On the investigation:
It will be important to secure the crash site to avoid "contamination" by the rebels. Malaysia, Ukraine and likely Russia will all need to be involved in the investigation.