NBC News is reporting that blood and urine samples taken from victims of last week’s chemical weapons attack in Syria show the presence of both chlorine and an unnamed nerve agent.

The samples suggested the presence of both chlorine gas and an unnamed nerve agent, two officials said. Typically, such samples are obtained through hospitals and or collected by U.S. or foreign intelligence assets on the ground. The officials said they were “confident” in the intelligence, though not 100 percent sure.

The Assad regime is known to have stocks of the nerve agent sarin, and has previously used a mixture of chlorine and sarin in attacks, say U.S. officials.

Officials also said that the U.S. has compiled intelligence from the U.S. and other countries, including images, that indicate the Syrian government was behind the weekend attack…

The assessment about the nature of this April’s chemical attack and its likely origin with the Assad regime will be presented to the president, said the official familiar with the intelligence.

The Assad regime has been dropping chlorine barrel bombs on its own citizens semi-regularly. Most of those attacks barely rate a blip in the news. But when the regime mixes in a nerve agent like sarin, the deadliness of the attacks goes up sharply as does international concern.

That’s exactly what happened last year. A chlorine-sarin mixture was dropped on Khan Sheikhoun, killing dozens and injuring hundreds more. That attack was determined to have been carried out by the Syrian air force, though Syria and Russia both denied it at the time. Ignoring those denials, President Trump responded with a cruise missile strike on the Syrian air base from which the attack was launched.

The NBC story above strongly suggests the attack last week was of the second variety, i.e. not simply chlorine but a mixture that also including a nerve agent, probably sarin. That hasn’t been confirmed “100 percent” because we don’t have on-the-ground access to the area where the attack took place. But it appears that’s where all the evidence is pointing even though Syria (and Russia) are once again denying everything. Even if inspectors are allowed in, they can only verify whether an attack happened, not who was responsible.

But it’s worth noting that French President Emmanuel Macron is also saying he has seen “proof” that Syria was responsible for the attack, though he isn’t explaining how he knows:

The French leader had previously said any strikes would target the Syrian government’s “chemical capabilities”.

He did not give the source of his information but said: “We have proof that last week chemical weapons, at least chlorine, were used by the regime of Bashar al-Assad.”

Asked in a TV interview whether France would join strikes on Syria, he said: “We will need to take decisions in due course, when we judge it most useful and effective.

“Regimes that think they can do everything they want, including the worst things that violate international law, cannot be allowed to act.”

Meanwhile, President Trump has already warned Syria would pay a price and that missiles were coming. He tried to walk that back a bit today or at least make it vaguer:

It makes sense to verify everything carefully before launching an attack, but given that Syria has done this before (and lied about it), it really doesn’t seem like much of a stretch to believe they’ve done it again.