[Detrytus]

US constitution says that starting a war must be authorized by Congress, president has no authority to do it on his own.

The problem is: over time the US grew so powerful, that the definition of "war" became blurry. "No, we are not at war, our soldiers are just dropping bombs on Iran for fun and profit".

EDIT: Another problem, of course, is that current member of Congress have no balls to stand up to Trump and reclaim their constitutional powers.

[terminalshort]

Congress made its mistake a long time ago. Power is very difficult to reclaim once it has been relinquished. And it didn't even take a Caesar crossing the Rubicon in our case.