It's the Department of Defense.
[1] "only an act of Congress can formally change the name of a federal department." https://en.wikipedia.org/wiki/Executive_Order_14347
(edited to add the url I omitted)
Only Congress can declare war and Congress has the "power of the purse".
"You can just do things" (evil edition).
Only Congress can declare war and Congress has the "power of the purse".
"You can just do things" (evil edition).