Within hours, officials and aviation experts voiced growing certainty that Flight 17 had been shot down by a surface-to-air missile fired from the disputed territory - marking a dangerous point-of-no-return in the escalating conflict between Ukraine and leader Vladimir Putin's Russia.
Vice President Joe Biden told a meeting of liberal activists in Detroit that the Amsterdam-to-Kuala Lumpur flight "apparently has been shot down - shot down, not an accident, blown out of the sky. Nearly 300 souls have been lost . . . and there are many questions that need to be answered, and we'll get those answers."
Speculation immediately turned toward Russia-backed separatists fighting along Ukraine's eastern border, where the jumbo jet went down. The apparent shoot-down came after several Ukrainian military planes and helicopters had been downed in the region, after reports that rebels fighting the Ukrainian government had last month seized a base with a powerful Buk surface-to-air missile system.
"We warned you, stay away from our skies," said a social-media post that was attributed to a prominent eastern Ukrainian rebel leader who goes by the name of Igor Strelkov - but the post was quickly deleted and could not be verified.
Also not immediately known was the number of American citizens who were on the flight, although early reports suggested it could be as many as 23. There were no survivors of the crash.
The air tragedy was also haunted by a number of eerie coincidences - most notably the fact that just four-and-a-half months ago another Malaysia Airlines jumbo jet, Flight 370, vanished on its route from Kuala Lumpur to Beijing under unknown circumstances and has not been found.
Closer to home, yesterday was also the 18th anniversary of the explosion off Long Island that brought down TWA Flight 800 with 230 people aboard, including 16 high school students and five adult chaperones from the Pennsylvania town of Montoursville.
The political fallout from yesterday's disaster is likely to be extensive. Earlier this week, the Obama administration had already increased economic sanctions against Russia and Putin's inner circle over increased militarism in eastern Ukraine, where Russia has already annexed the province of Crimea.
Republican Sen. John McCain, of Arizona, said "if it is the result of either separatist or Russian actions mistakenly believing this was a Ukrainian war plane, I think there's going to be hell to pay and there should be."
Russia and Ukraine were once united under the flag of the former Soviet Union, but tensions have steadily increased since the breakup of that communist empire in 1991. Last fall, revolution in the streets of Kiev ousted Ukraine's pro-Putin president, which in turn prompted Putin to seize Crimea and sparked a pro-Russia uprising in the eastern region, where the commercial jetliner was shot down.
Already, a possible complication in investigating the crash emerged when rebels who control the area where Flight 17 went down said they were sending the plane's so-called "black box" to Moscow, thwarting western aviation investigators.
Ukrainian President Petro Poroshenko called the downing of the jet an "act of terrorism" and demanded an international investigation.
Ukraine's security services produced what they said were two intercepted telephone conversations that indicate rebels were responsible. In the first call, the security services said, rebel commander Igor Bezler tells a Russian military intelligence officer that rebel forces shot down a plane.
In the second, two rebel fighters - one of them at the crash scene - say the rocket attack was carried out by a unit of insurgents about 25 kilometers (15 miles) north of the site. Neither recording could be independently verified.
- The Associated Press contributed to this article.
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