"Preliminary surveillance data" examined by the Pentagon suggests the missing Malaysia Airlines jet did not explode over the South China Sea, according to The New York Times.
The newspaper cited a U.S. government official who spoke on the condition of anonymity as suggesting "a system that looks for flashes around the world" had not identified any sign of a blast. NBC News could not immediately confirm the report.
More than 36 hours after the last contact with Flight MH370, officials said Sunday they were widening the search to cover vast swathes of sea around Malaysia and off Vietnam.
Among the 239 people aboard the Boeing 777-200ER were two passengers using stolen passports.
U.S. officials told NBC News on Saturday they were investigating terrorism concerns.
Pilots and aviation experts said an explosion on board appeared to be the likely cause of the disaster. The plane was at cruising altitude, the safest phase of flight, and likely would have been on autopilot.
"It was either an explosion, lightning strike or severe decompression," a former Malaysia Airlines pilot told Reuters. "The 777 can fly after a lightning strike and even severe decompression. But with an explosion, there is no chance. It is over."
John Goglia, a former board member of the National Transportation Safety Board, said that the lack of a distress call suggested that the plane either experienced an explosive decompression or was destroyed by an explosive device.
"It had to be quick because there was no communication," Goglia said. He said the false identities of the two passengers was "a big red flag".
Reuters contributed to this report.