Malaysia PM: Jet's route was 'declared safe'

Malaysia Prime Minister Najib Razak said Thursday that the flight path of a jetliner that was believed to have been shot down over Ukraine was declared safe by international aviation officials.

Malaysia Airlines Flight 17, which was a Boeing 777, crashed on Thursday during a flight from Amsterdam to Kuala Lumpur, Malaysia, in an apparent act of terrorism.

The airplane was carrying 280 passengers and 15 crew members.

Malaysian officials said Thursday that the flight's path was cleared before its take-off and that the airplane's pilot did not issue any distress signals.

"The aircraft’s flight route was declared safe by the International Civil Aviation Organization," Najib said. "And International Air Transportation Association has stated that the airspace the aircraft was traversing was not subject to restrictions."

The Federal Aviation Administration said Thursday that it had warned U.S. airlines about flying over Ukraine in April, when a dispute over the country's shared border with Russia first began.

"Due to the potential for conflicting Air Traffic Control (ATC) instructions from Ukrainian and Russian authorities and for the related potential misidentification of civil aircraft, United States (U.S.) flight operations are prohibited until further notice in the airspace over Crimea, the Black Sea, and the Sea of Azov," the agency said in an April 3 notice.

The agency said Thursday afternoon that the Malaysia Airlines flight that crashed was not operating in the specific airspace that was included in its April 3 warning, however.

Ukrainian officials alleged on Thursday that the flight was shot down by Russian separatists who have been battling Kiev.

Vice President Biden also suggested the plane was intentional "blown out of the sky" during a speech on Thursday afternoon.

Najib promised Thursday to bring any potential perpetrators to justice.

"At this early stage, however, Malaysia is unable to verify the cause of this tragedy," he said. "But we must – and we will – find out precisely what happened to this flight. No stone can be left unturned. If it transpires that the plane was indeed shot down, we insist that the perpetrators must swiftly be brought to justice."

Thursday's accident is the second high-profile incident involving a Malaysia Airlines flight this year.

Earlier this spring, a Malaysia Airlines flight disappeared, prompting a prolonged multinational search.

The first missing plane, Malaysia Airlines Flight 370, has yet to be found, baffling lawmakers and aviation officials alike.

That plane was carrying 239 passengers at the time of its disappearance.

Najib said Thursday was "a tragic day, in what has already been a tragic year, for Malaysia."