Answer: president is to wage wars as commander in chief while Congress has the power to declare wars--in fact to authorize hostilities at any level--and fund them.
Explanation: presidents can order U.S. troops to fight when the country is attacked or attack appears imminent but chief executives from both major parties often differ with Congress over their ability to initiate military force in other combat situations. Presidents have demonstrated greater power to wage wars since the end of World War II. "The president has been commander in chief since 1789, but this notion that they can go to war whenever they want, and [ignore] Congress, that’s a post-World War II attitude," says Louis Fisher, scholar in residence at the Constitution Project (and former specialist in constitutional law at the Library of Congress)