'Significant Possibility' Russian Plane Was Brought Down by Explosive Device, UK Says

— -- There is a "significant possibility" that the Russian jet that crashed in Egypt this weekend was brought down by an explosive device, British Foreign Secretary Philip Hammond said today.

As a result, British officials announced that no U.K. flights will fly to Sharm el Sheikh for the foreseeable future, and the U.K is working to return the 2,000 British tourists in Sharm el Sheik.

The government is advising against all but essential travel through Egypt's Sharm el Sheikh airport. The Irish Aviation Authority also directed Irish airlines not to operate from or to the airport.

While the investigation into what caused the plane crash is ongoing, the plane "may well have been brought down by an explosive device," a spokesman for the office of the British prime minister said earlier today.

The investigation is led by officials in Egypt and aided by experts from Russia, Ireland and Airbus, an aircraft manufacturer based in France.

Egypt's president was in the U.K. and was expected to meet with Prime Minister David Cameron.

White House press secretary Josh Earnest responded to the British government's decision today, but did not say whether the U.S. has any new insight as to what caused the plane to crash.

“We obviously have a strong desire to get to the bottom of what exactly happened there,” Earnest said. “The British officials are announcing steps that they have concluded are in the best interests of ensuring the safety of the British traveling public. And I'll let them speak to any decisions that they've made about that.”

Earnest said the U.S. government has a "heightened" awareness of the risk that ISIS or other extremists could have taken down a commercial jet.

While infrared flashes were observed by an American military satellite in the vicinity of a the plane, officials cautioned that it was too early to tell what they were, or even if they were connected to the plane.

A defense official said there were flashes picked up by satellite infrared sensors -- designed to detect missile launches -- around the same time that the plane was passing over the Sinai Peninsula.

The official said that if the flashes are connected to the aircraft, it might indicate that something happened in the air or by the plane's impact on the ground. But there was military activity in the area, so they may not be related, the official said.

According to the official, a missile strike was unlikely because no trail was detected by satellite.

The Russian Metrojet plane mysteriously crashed in the Egyptian desert early Saturday, killing all 224 people on board. The plane's black boxes are still being analyzed.

The Cockpit Voice Recorder is partially damaged, the Egyptian Civil Aviation Ministry said today, adding that it will require a lot of work to extract its data.

The head of the U.S. National Counterterrorism Center, Nick Rasmussen, said this week the intelligence community so far has no information to corroborate any specific nexus to terrorism. But he emphasized that "it's an unfolding" situation.

Monday the U.S. Embassy in Cairo issued a warning instructing its employees not to travel anywhere in the Sinai Peninsula pending the outcome of the investigation into the crash. The embassy called it a "precautionary measure."

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