Coast Guard, Navy and Marines are naval services.
The Air Force isn’t military, it is an air service.
The Army is a military service.
All can kill the enemy and all of them can die bravely if necessary.
“of or relating to soldiers or the armed forces (such as the army, navy, marines, and air force”
The Navy is governed under the Uniform Code of Military Justice, is it not?
Finally, the Federal Government disagrees with you:
“The U.S. Military consists of five active-duty Services and their respective Guard and Reserve units. All branches are equal parts of the United States Uniformed Services, headed by the president as commander in chief. The Army, Marine Corps, Navy and Air Force fall under the jurisdiction of the Department of Defense (DoD). The Coast Guard reports to the Department of Homeland Security during peacetime and to the DoD (by way of the Navy) during wartime.”