We have "sort of" been at war against ISIS for a very long time.  Is that OK with you if we try to defeat enemies who blow things up, kill innocent bystanders they call infidels, chop off people's heads, rape and mutilate women and young girls, etc.?  I mean, they don't live in one country that we can declare war against, but is it OK if we go after them anyway?   A long list of civilized countries lauds Trump's retaliation for a crime against humanity.  Obama was too chicken to do it, or perhaps he was sympathetic with murderer Assad.