The Department of Defense uses a variable number of base locations depending on its level of operations. With ongoing warfare in Iraq and Afghanistan in 2003, the United States Air Force used 35 bases, while in 2006 it used 14, including four in Iraq. The United States Navy maintains one major base and one smaller installation, with extensive deployments afloat and ashore by U.S. Navy, U.S. Marine Corps and U.S. Coast Guard ships, aviation units and ground units.