The services and their missions There are five military services. The primary mission of one, the Coast Guard, is to protect the coastline, although it does have some missions abroad. It also has rescue and law enforcement responsibilities. The Coast Guard has had different governmental homes. Currently it is part of the Department of Homeland Security, although in time of war it has been placed under the Navy. The focus here, however, is on the four military services located in the Department of Defense (DOD) and housed in the Pentagon. Thus, the Coast Guard will not be discussed further. As will be seen, the missions and cultures of the four DOD services are quite different.