The ABC News report on this latest development takes the usual caution with the report, but it’s difficult to see any other possibility for a terror attack on the Russian flight out of Sharm el-Sheikh except for a suicide bomber. This flight was a charter by a tour group, though, which would make that kind of infiltration a little difficult. If this was a terror attack, then the most likely scenario would be that an insider at the airport smuggled the bomb on board, right? Or airport security that was so bad that anyone could walk on the plane with a bomb?

“ISIS may have concluded that the best way to defeat airport defenses is not to go through them but to go around them with the help of somebody on the inside,” Rep. Adam Schiff, D-Calif., who has received classified briefings on the investigation, said on ABC News’ “This Week” Sunday.

American authorities told ABC News that electronic intercepts of ISIS, both before and after the crash, indicated that ISIS was in communication with someone at the airport.

The first hard evidence of a possible bomb was revealed this weekend by Egyptian officials who said the cockpit voice recorder, the CVR, captured a distinct but undetermined noise just before it stopped working.

“A noise was heard in the last second of the CVR recording,” an Egyptian official said.

ABC notes that the US is not participating in the review of the Metrojet attack, but that’s not unusual in and of itself. Five nations are combining efforts for the probe: Russia and Egypt for obvious reasons, Ireland as the plane was registered there by the charter company, and France and Germany as the core nations of the EU. The US has remained in contact with the investigation, and their intelligence will likely help the probe reach a conclusion, so it’s not necessary for us to bigfoot our way into the effort.

It will be necessary to pay attention to its findings, especially in regard to infiltration. Brian Ross notes in the video that this is already a concern for the Department of Homeland Security. In June, the Senate committee overseeing DHS discovered that their screeners missed 73 people with potential ties to terrorism in their airport-hiring screening process, because DHS didn’t give TSA access to the full terror watchlist produced by the US intel community. Supposedly, the reorganization that created DHS was supposed to solve this kind of stovepiping. Clearly it hasn’t, and this attack should get Congress moving in forcing improvements in the screening process.

We had better start taking this vulnerability seriously. Our enemies certainly do.