Russia clearly thought before the election that Clinton would intervene in Syria and Trump would not. Remember that was one of the bigger differences between them on the campaign trial with Trump and his supporters arguing against antagonizing Russia. Maybe they calculated wrong or maybe this was a one-off.
Russia are certainly completely overreacting to a missile strike on a military base. They're talking about responding with force next time America does this! Literally threatening a war with the United States.
I think Jonhson might be onto something with increasing sanctions against Russia:
https://www.thetimes.co.uk/edition/n...utin-7kcpstplc