The first missile in the U.S. arsenal used against Iranian targets in Saturday’s pre-dawn strike was the Tomahawk, a long-range cruise missile launched from Navy ships and submarines. About half the length of a standard telephone pole, the Tomahawk flies at the speed of a commercial airliner and can carry a 1,000-pound warhead about the distance from Washington, D.C., to Miami. Fired from destroyers or submarines positioned hundreds...