Article 1, Section 8, of the US Constitution: "The Congress shall have Power ... to declare War" ...
That's right children, only Congress can authorize the use of military forces against another nation ... but Congress knows they can't always meet and vote quick enough to properly defend the United States ... so they passed a law that allows the President to use the military for 60 days without congressional approval ... the War Powers Act ... and the President has to report these military operations to Congress in a timely manner ...
If The Donald can get into Iran, defeat them, and have the troops back out in 60 days ... without spending any money ... then he is free to do so without congressional approval ... if The Donald wants a trillion dollar emergency appropriation and longer than 60 days ... then he'll need House approval ...
It's a shame so many people scream about protecting our system of government without understanding what that system is ... do you know nothing about late 12th Century English history, and how that impacted mid 18th Century English history? ... the same people who think cutting taxes is the best way to fully fund our public schools ...