This is a very big development in a story that first started to develop last Friday. From the Associated Press:

The official said a drone operated by Russians was flying over a hospital as victims of the attack were rushing to get treatment. Hours after the drone left, a Russian-made fighter jet bombed the hospital in what American officials believe was an attempt to cover up the usage of chemical weapons.

The official said the presence of the surveillance drone over the hospital couldn’t have been a coincidence, and that Russia must have known the chemical weapons attack was coming and that victims were seeking treatment.

Later the story contains this paragraph about one of the new developments in the story [emphasis added]:

Until Monday, U.S. officials had said they weren’t sure whether Russia or Syria operated the drone. The official said the U.S. is now convinced Russia controlled the drone. The official said it still isn’t clear who was flying the jet that bombed the hospital, because the Syrians also fly Russian-made aircraft.

That detail about U.S. officials not being sure who operated the drone is actually not true. In fact, I specifically pointed this out when I wrote about it last Friday. It’s true that the AP said Friday the drone was either Russian or Syrian. However, CNN had a report Friday afternoon which made clear the drone was Russian:

A US defense official says intelligence shows a Russian drone flew over the hospital in Idlib that was treating victims of the chemical attack, prior to the site being later bombed by an unknown aircraft.

The Russians operate drones in the area routinely so the Pentagon cannot be certain the drone operator even knew what was happening, but the drone was a Russian asset. The US military has a variety of classified technical means to determine who is operating aircraft in the region.

Note there was still some doubt last week if the drone’s presence indicated Russia was complicit in the attack, but CNN had reported the drone itself was Russian. So what’s new today is apparently the confidence that this was not a coincidence and that a Russian-made jet bombed the hospital.

As the AP admits, their source, “didn’t provide all the details for the military and intelligence information that form the basis of what he said the Pentagon has now concluded.” That means we have a series of as yet unproven assumptions. First, we don’t know how the U.S. is certain this was a Russian drone. Second, we don’t know why they’re so sure it wasn’t a coincidence (as CNN suggested might be the case Friday) the drone was there. Maybe the release of a timeline would help explain that. Third, even if Russia was complicit, does that prove they were aware of the attack in advance? In other words, couldn’t Russia have found out about a rogue chemical attack by Syria after the fact and then acted to cover it up?

I’m not saying I doubt the U.S. conclusion, only that the Russian propaganda outlets are going to have a field day with this until it is backed up with a lot more detail. But if this report is accurate and Russia knew about (and participated in trying to cover up) the chemical attack, they are involved in a war crime.  The obvious question is what happens now?