Very few would argue with the claim that the President's role as Commander-in-Chief is the greatest formal power that a president possesses. Yet, in the Constitution, only Congress has the authority to formally "declare war." Presidents for the last 60-70 years have openly stated that they do not need Congressional authorization to use the military to pursue America's interests on the global stage. As proof, America has not formally declared war since WWII. So, Korea, Vietnam, Gulf War, Iraq War, Afghanistan, and now Syria have all been military exercises, but not wars in the Constitutional sense.