Is USA at war though?

In the modern sense, yes. We no longer declare wars explicitly, nor do we limit that decision to Congress. Trump's decision to attack these targets is consistent with every other conflict we've engaged in since before either of us were born... national security threats. Even if you believe the dope itself to be no great national security threat, that's just their payload today, maybe next time they'll smuggle in a nuke or whatever.

Of all the things that people on the left might find objectionable about Trump, this should be at the very far bottom of the list.