Yes, it is part of the military ( along with the Army, Navy, Air Force and, Marines ) and all members of the Coast Guard are subject to the Uniform Code of Military Justice. It is one of seven (yes there are seven) uniformed services. It is organized under the Department of Homeland Security, but become part of the Department of the Navy during wartime or when the President deems so. The other two Uniformed Services are the United States Public Health Service Commissioned Corps and the National Oceanic and Atmospheric Administration Commissioned Corps.