"A Declaration Of War is a formal act by which one state announces existing or impending war activity against another. The declaration is a performative speech act by an authorized party of a national government." -Wikipedia So, as the Congressman said, the President is not ABLE to declare war.

"performative" being a key word here - t**** skipped ahead to the actual act of war (bombing) - while intentionally failing to brief the Dems in Congress first

For the United States to declare war, Congress must make a "performative" act, that is a declaration. Only Congress can do that, not the president. Trump attacked Iran, but we are not at war with them – and, because they have not declared war, they are not at war with us. Of course, it still sucks.