I'm going to try to be as precise as possible when I say this. With regards to the alleged chemical attack on 2017 that lead to Trump calling in missile strikes, The Syrian govt did attack one of those facilities, but there is no evidence to suggest that they were aware that sarin gas was located in the facility, nor was there any evidence that they had a motive to intentionally have an alleged saron gas release. There is speculation that the gas was staged there as by "White Helmets" or the Free Syrian Army in order to provoke a US response or it was simply collateral damage done without the intention of having an alleged gas release.