France has evidence that Syria used chemical weapons against its own citizens, French President Emmanuel Macron President said this afternoon, five days after a suspected chemical attack there.

“We have the proof that last week ... chemical weapons — at least chlorine gas — were used by [President Bashar] Assad's regime," Macron told a French today.

As for a response, "We have to make a decision at the right moment, when we will consider it useful and the most effective,” Macron said, adding that he is "working closely" with the United States.

But the international watchdog charged with independently verifying the chemical attack, the Organization for the Prohibition of Chemical Weapons (OPCW), has not yet been given access to the site of the alleged chemical attack in Douma.

PHOTO: French President Emmanuel Macron arrives at an elementary school to attend a one-hour interview with French news channel TF1, in Berd'huis, France, April 12, 2018. (Gonzalo Fuentes/Reuters) More

The OPCW's inspection team is on its way to Syria and will start work Saturday, the organization tweeted today. But getting access to the site may still be a challenge. The Russian military this morning said it was completely in control of the once rebel-held Douma and had raised a Syrian flag in the suburb just outside of Damascus.

The French president's conclusion confirms an independent analysis published Wednesday by a website called Bellingcat, based on open-source material.

Eliot Higgins, a British researcher and independent journalist, runs Bellingcat, which digs into the digital forensics of events mostly inside Syria, focusing on the weaponry used in attacks, both conventional and chemical.

He has become in recent years one of the foremost experts on the munitions used in the Syrian conflict and a vital resource to journalists.

PHOTO: This image released early Sunday, April 8, 2018 by the Syrian Civil Defense White Helmets, shows a child receiving oxygen through respirators following an alleged poison gas attack in the rebel-held town of Douma, near Damascus, Syria. (Syrian Civil Defense White Helmets via AP) More

As soon as Higgins saw the reports of a chemical weapons attack rolling in Sunday, he got to work.

"Reports indicated that a significant number of people, including children, had been killed by these attacks," Higgins wrote at the top of his analysis.

Eyewitness accounts from the ground came in the form of disturbing videos showing children frothing at the mouth, unable to breathe.

Frame by frame, Higgins went through the video and photos that emerged, identifying markings on the buildings in order to confirm the video and pictures were from Douma, a suburb outside of Damascus that activists and doctors said was attacked by the Assad regime.

After they had identified the building featured in most of the photos and videos, Higgins' team members were then able to match the video released by the Russian foreign ministry allegedly showing Russian forces visiting the site of the attack to the same building. His team is confident that the videos from activists and the Russian foreign ministry handout video were shot at the same building.

The entrance of the building they're entering was filmed in another video, showing corpses being removed from the building (graphic) https://t.co/xvDkLG7HfN pic.twitter.com/yZl9kiGXLd — Eliot Higgins (@EliotHiggins) April 10, 2018

The same entrance is also visible in this video (graphic), showing bodies inside the apartment building that was hit. It's also possible match corpses filmed inside the building to corpses taken outside. https://t.co/F9lkdZb4z8 pic.twitter.com/hojcBFERE8 — Eliot Higgins (@EliotHiggins) April 10, 2018

The Russian foreign ministry said their samples were clean. The “Russian specialists” who visited the site “found no traces of chlorine or any other chemical substance used against civilians," according to Foreign Minister Sergei Lavrov.

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