The six-page French document – drawn up by France’s military and foreign intelligence services and seen by said it reached its conclusion based on samples they had obtained from the impact strike on the ground and a blood sample from a victim.

“We know, from a certain source, that the process of fabrication of the samples taken is typical of the method developed in Syrian laboratories,” Foreign Minister Jean-Marc Ayrault told reporters after presenting the findings to the cabinet.

“This method is the signature of the regime and it is what enables us to establish the responsibility of the attack. We know because we kept samples from previous attacks that we were able to use for comparison.”

Among the elements found in the samples were hexamine, a hallmark of sarin produced by the Syrian government, according to the report.