Stunning.

The latest U.S. intelligence suggests that the crash of a Russian passenger jet in the Sinai over the weekend was most likely caused by a bomb on the plane planted by ISIS or an ISIS affiliate, according to a U.S. official familiar with the matter.

But the official stressed a formal conclusion has not been reached by the U.S. intelligence community.

“There is a definite feeling it was an explosive device planted in luggage or somewhere on the plane,” the official, who is familiar with the latest U.S. intelligence analysis of the crash, told CNN.

British intelligence also said this morning that they’re leaning towards terror being the cause of the crash. What’s the evidence? For starters, satellites picked up a large flash of light around the plane right before it went down. It wasn’t a missile that caused that, as the launch would have been detected. It might be an exploding fuel tank, possibly caused by some sort of accidental technical malfunction, but a Russian news agency reported that everything sounded normal in the cockpit as recently as four minutes before the plane crashed. Either a fuel tank exploded with no warning to the crew that it was in distress or something else exploded.

Then there’s this:

IC sources tell me we've picked up non-specific jihadist chatter indicating #ISIS (or related) involvement in loss of #7K9268…FWIW.

— John Schindler (@20committee) November 4, 2015

The WSJ has more details:

The Egyptian affiliate of Islamic State [the “Sinai Province”], meanwhile, issued Wednesday a fresh claim of responsibility for downing the plane and said it would reveal further details of its involvement in due course…

The new audio claim, released on social media by the Islamic State affiliate, was carefully worded, with the speaker not saying explicitly how the airplane crashed, killing all 224 people on board…

The statement, the second such claim by the militant group, points to a troubling aspiration by Sinai Province, which until now has limited the vast majority of its attacks to government targets. Regardless of the doubt surrounding its military ability to take down an aircraft the insurgency is now openly expressing a desire to kill scores of civilians.

The Sinai Province operates in the same northern region of the Sinai where the jet went down. In other words, not only are public claims of terrorism being made. but as Schindler says, intercepts of private jihadi chitchat suggest that there might be something to it.

Why would ISIS or one of its affiliates target Russia? The obvious answer is payback for Putin’s assistance to Assad in Syria, but it’s more complicated than that. ISIS isn’t Russia’s main target in Syria, after all. It’s the somewhat less fanatic Sunni rebels who are the main target because they’re the ones being backed by the west and they’re the ones whom the White House is counting on to become the nucleus of a new Sunni-led government once Assad is gone. Arguably it’s in Russia’s interest to go easy on ISIS in order to make Assad more palatable to the west as the only man in Syria capable of holding back the jihadi hordes. The more persistent the threat from ISIS, the more insistent Russia can be that Assad is the only answer. Blowing up one of Putin’s passenger jets means throwing that tacit bargain away. Which, I take it, also explains why the U.S. and UK are so eager to leak these findings. Not only will it wound Putin’s prestige at home if word spreads in Russia that this was terrorism, not only will it force him to retaliate against ISIS to show strength, but it’s evidence that the White House can tout to show that Obama was right — Putin’s gotten himself into a “quagmire” in which he’ll have no choice but to escalate as ISIS and its sympathizers escalate with him. Makes me wonder if the official story in Moscow won’t be that the crash was an accident, period, and that’s all they have to say about it.

As for why ISIS would target Russia, maybe this was a freelance operation by the Egyptian affiliate designed to show the local strongman, Sissi, that jihadis can do big things even in the new “secure” post-Muslim-Brotherhood Egypt. Or maybe ISIS itself concluded that there’s more to be gained in propaganda by bloodying Putin’s nose than there is to be lost by becoming a more prominent target for Russian military planes. Putin’s become a Shiite hero in Iraq and Syria for attacking the Sunnis on Assad’s behalf. Go figure that the most notorious Salafist jihadi outfit out there might want to impress their Sunni constituents — including and especially in Chechnya — by proving that even Russian targets aren’t beyond their reach. And if they’re willing to do that to impress people, imagine what they might be willing to do to prove that they can hit the United States too. A lot of American natsec people are scrambling right now, I’ll bet.

if this latest intel proves accurate, this would be biggest (successful) terrorist attack on a plane since 9/11.

— Jake Tapper (@jaketapper) November 4, 2015