The 2nd Infantry Division ("Indianhead"; "2ID," "2nd ID", or "Second D") is a formation of the United States Army. Its current primary mission is the pre-emptive defense of South Korea in the event of an invasion from North Korea. There are approximately 17,000 soldiers in the 2nd Infantry Division, with 10,000 of them stationed in South Korea, accounting for about 35% of the United States Forces Korea personnel.

The 2nd Infantry Division is unique in that it is the only U.S. Army division that is made up partially of South Korean soldiers, called KATUSAs (Korean Augmentation to the U.S. Army). This program began in 1950 by agreement with the first South Korean president, Syngman Rhee. Some 27,000 KATUSAs served with the U.S. forces at the end of the Korean War. As of May 2006, approximately 1,100 KATUSA soldiers serve with the 2ID. There were also more than 4,748 Dutch soldiers assigned to the division between 1950 and 1954.