The National Defense Reserve Fleet (NDRF) consists of ships of the United States of America, mostly merchant vessels, that have been "mothballed" but can be activated within 20 to 120 days to provide shipping during national military emergencies, or non-military emergencies such as commercial shipping crises. The NDRF is managed by the U.S. Department of Transportation's Maritime Administration (MARAD). It is distinct from the United States Navy reserve fleets, which consist largely of warships.