Special to WorldTribune.com

Intercepted calls between Islamic State of Iraq and Levant’s (ISIL’s) affiliate in the Sinai Peninsula and the terror group’s leaders in Syria included discussions on the downing of a Russian plane, U.S. intelligence officials said.

A U.S. intelligence official told NBC News that a message that was transmitted before the crash of Russian Metrojet Flight 9268 stated that there would be “something big in the area.”

Experts now believe the Russian airliner was brought down as the result of an explosion in the plane’s luggage bay.

One official said “it’s 99.9 percent certain” that a bomb brought down the airliner that crashed in Egypt’s Sinai Peninsula last weekend, killing all 224 people aboard.

An official told CNN that U.S. and British intelligence found in the intercepted messages that ISIL jihadists were talking about the type of bomb and detonator used, and the intelligence officials were working to determine “whether that language was a true representation of what happened.”

Ayman al-Muqaddam, who is heading up Egypt’s investigation of the crash, said a noise was heard in the final second of the cockpit voice recording.

“All the scenarios are out on the table,” he said. “We don’t know what happened exactly.”

Muqaddam did not describe the noise investigators picked up but said “a spectral analysis will be carried out by specialized labs in order to identify the nature of this noise.”

The investigation includes experts from Egypt, Russia, France, Germany and Ireland.

Meanwhile, U.S. Homeland Security Secretary Jeh Johnson told CNN the U.S. is taking “precautionary interim steps” to increase security on international flights into the United States.

“ISIL is out there now active in a lot of different areas and, while this investigation is pending and because we have this group claiming responsibility, we believe it’s significant to do these things on an interim basis,” Johnson said.

  Ayman al-Muqaddam, Intercepted ISIL calls may have concerned Russian airliner, Jeh Johnson, Sinai Peninsula, WorldTribune.com