The War Powers Resolution limits the Presidents ability to take military action
Congress has the sole power to declare war, but in our modern world, there are circumstances under which the President can take military action. Those circumstances would be a limited authorization by Congress short of a declaration of war, and attack on a country with which we have a mutual defense treaty, or an attack, or imminent attack on the US, or it’s forces abroad.
When acting under the War Powers Resolution, the President is required to notify Congress within 48 hours of his actions and has 60 days to act without further Congressional approval.
Iran has launched ballistic missiles against US Troops from within Iranian territory, so the requirements of the WPR have been met, but I think it would be useful for President Trump to ask for a declaration of war against Iran, just to put them on notice that they have pushed a bit too far.
Perhaps the people of Iran need “A Taste of Armageddon”