U.S. officials told NPR that they believe the plane was shot down by a surface-to-air missile, but it was unclear whether the missile came from Ukraine or across the border in Russia. Ukraine, and the area where the plane crashed in particular, has been embroiled in a separatist insurgency for months.
Flightradar24.com, a flight-tracking website, tweeted that there were now fewer flights over Ukraine. Several airlines — including Delta, KLM, Emirates and Air France — all issued statements confirming that they were avoiding Ukrainian airspace.
#AirFrance is monitoring the situation in realtime and took the decision not to fly over East of Ukraine since hearing of accident #MH17 1/2
Eurocontrol, the agency that coordinates and plans air traffic for all of Europe, also released a statement that said it was informed that routes from the ground in eastern Ukraine would be closed. Eurocontrol said that "all flight plans that are filed using these routes are now being rejected" and that they would remain closed until further notice.
NPR correspondent Geoff Brumfiel said on All Things Considered this afternoon that airlines have changed their routes in the past over conflict zones, such as Syria. But the situation in Ukraine has an added complication.
"Now, there have been some warnings issued about specifically Crimea, because interestingly enough both Russia and ... Ukraine claim Crimean airspace, so there were worries about whether air traffic control communications could become confused," Brumfiel says. "But neither the FAA [nor] the International Civil Aviation Organization issued such warnings about this area."