Under what conditions does the president have the power to order American troops into battle without congressional approval?

Answer 1

Under the Constitution, the president is commander in chief of all the armed forces. The chain of command runs from him to the secretary of defense and then to the specific commands in the military. The president, under this power, can deploy the armed forces to protect the nation if it is under attack, without first asking Congress to declare war. Since September 11, the military power of the President has increased. Congress passed the War Power Resolution which gives the President the power to retaliate against any person, organization, or state which the President considers a terrorist threat, and also the power to use military force against a foreign nation suspected of supporting terrorist groups. The President can deploy a preemptive use of military force against terrorist organizations whether they can be linked to a specific terrorist act or not.

Addition(Marine Lessons): All of the United States Military Services' chain of command leads to Congress, but The United States Marines fall directly under the President of the United States. The president can literally walk up to a Marine and order him to do things that undermine his commanding generals. This makes it very important who the president is for Marines. I personally enlisted under Bush (jr.), and left the Marines after 5 1/2 years under Obama. The Marines do not need congressional approval to be sent somewhere for short periods of time.