Investigators in Malaysia are voicing skepticism that the airliner that disappeared early Saturday with 239 people on board was the target of an attack, U.S. and European government sources close to the probe said.
The fate of the Malaysian airliner that vanished about an hour into a flight to Beijing remained a mystery, as a massive air and sea search, now in its third day, failed to turn up any trace of the Boeing 777 plane.
Neither Malaysia's Special Branch, the agency leading the investigation locally, nor spy agencies in the United States and Europe have ruled out the possibility that militants may have been involved in downing Malaysia Airlines Flight MH370.
But Malaysian authorities have indicated that the evidence so far does not strongly back an attack as a cause for the aircraft's disappearance, and that mechanical or pilot problems could have led to the apparent crash, the U.S. sources said.
"There is no evidence to suggest an act of terror," said a European security source, who added that there was also "no explanation what's happened to it or where it is."
Meanwhile, dozens of ships and aircraft from 10 countries were still scouring the seas around Malaysia and south of Vietnam as questions mounted over possible security lapses that could have led to a downing of the Boeing 777-200ER after it climbed to an altitude of 35,000 feet (10,670 meters).
Interpol confirmed on Sunday at least two passengers used stolen passports and said it was checking whether others aboard had used false identity documents.
Even so, one U.S. source said Malaysian authorities were leaning away from the theory that the plane was attacked. Their view was mostly based on electronic evidence that indicates the flight may have turned back toward the Malaysian capital of Kuala Lumpur before disappearing.
Even that information has not been clearly confirmed, and investigators and intelligence sources say the fate of the Flight MH370 is still shrouded in mystery.
One reason was that the aircraft had failed to make automatic contact with a flight data-monitoring system after vanishing from radar screens, two people familiar with the matter said on Monday. Such contact could have helped investigators determine what happened.
The aircraft was equipped with a maintenance computer capable of talking to the ground automatically through short messages known as ACARS. "There were no signals from ACARS from the time the aircraft disappeared," a source involved in the investigations said.
Also raising doubts about the possibility of an attack, the United States extensively reviewed imagery taken by spy satellites for evidence of a mid-air explosion, but saw none, a U.S. government source said. The source described U.S. satellite coverage of the region as thorough.
