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While many have speculated that a missile may have struck a Russian commercial airliner that went down over Egypt's Sinai peninsula, U.S. officials are now saying satellite imagery doesn't back up that theory.

A senior defense official told NBC News late Monday that an American infrared satellite detected a heat flash at the same time and in the same vicinity over the Sinai where the Russian passenger plane crashed.

Related: Metrojet Rules Out Technical Fault as Cause of Crash in Sinai Peninsula

According to the official, U.S. intelligence analysts believe it could have been some kind of explosion on the aircraft itself, either a fuel tank or a bomb, but that there’s no indication that a surface-to-air missile brought the plane down.

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That same infrared satellite would have been able to track the heat trail of a missile from the ground.

"The speculation that this plane was brought down by a missile is off the table," the official said.

A second senior U.S. defense official also confirmed the surveillance satellite detected a “flash or explosion” in the air over the Sinai at the same time.

According to the official, "the plane disintegrated at a very high altitude," when, as the infrared satellite indicates, "there was an explosion of some kind."

That official also stressed “there is no evidence a missile of any kind brought down the plane.”

Russian officials first said Sunday that it appeared the plane had broken up in midair — fueling speculation of a possible plot involving explosives — and officials on Monday did little to dispel those fears.

When asked whether a terrorist attack could have downed the plane, Kremlin spokesman Dmitry Peskov said no theory could be ruled out, according to Reuters.

The Metrojet-operated Airbus A321 crashed Saturday in Egypt's Sinai peninsula, killing all 224 on board. The local ISIS affiliate claimed responsibility for shooting it down — but officials dismissed that as impossible by saying the militants lacked the weapons to do so.

And U.S. Director of National Intelligence James Clapper told a "Defense One" conference Monday that there was not yet any "direct evidence of terrorist involvement" in the crash.