Article I, Section 8: The Delegated Powers

"The Congress shall have Power To lay and collect taxes...

and

"...borrow money on the credit of the United States."

Congress defers to presidents on military matters, but war is something that only the country's law making body can officially declare.

"The Congress shall have the power to... declare war..."

This has empowered Congress further than some expected when the Constitution was drafted in 1787.

Congress may "regulate Commerce with foreign Nations, and among the several States, and with the Indian Tribes."