Is there any evidence the Syrian regime actually carried out the chemical weapons attack? Jaish al Islam, the Islamist group in control of Douma at the time of the alleged gas attack, had itself been accused of using gas against Kurdish fighters in 2016 . This is briefly mentioned quite a long way down this story:

https://www.thedailybeast.com/one-kurdish-neighborhood-in-the-crossfire

The Syrian regime had basically won the conflict, it doesn't make sense that they would launch a chemical attack in the full knowledge that it would no doubt draw in western countries. Now, on the other hand, it might make sense to launch an attack to draw in western countries if you were the Islamist group losing the conflict.

It all seems very familiar...drawn into a conflict we're not interested in and dropping bombs again without any evidence. We're assured the plan is not regime change, however, it seems the US and U.K. are determined not to have Assad in control...his links with Iran have to many implications...