The Navy said Wednesday that it would conduct random blood-alcohol tests on sailors in the United States starting next month. The tests are part of the 21st Century Sailor and Marine initiative by the Navy secretary, Ray Mabus, intended to improve the well-being of sailors and Marines after more than a decade at war. The Marines last month announced their own random alcohol tests. While alcohol has long played a part in the Navy’s culture, Navy officials stressed they were not trying to stop sailors from drinking, but were concerned about their health and safety. Any sailor whose blood-alcohol level is .04 or higher when reporting for duty will not be allowed to work.