I don’t think US has to much motive. We’re already there.
UK however did release this week an outside agency confirmed the nerve agent was used by Russia in the UK. Syria offers a nice proxy for revenge.
Israel hit an Iranian installment a day~ after the after the alleged attack… No one batted an eye. Syria’s spokes woman also said that coming ahead Israel is going to be the biggest loser in this situation.
That being said, could have been Syria, we’ll probably never know.