Submarines of all types are used to attack and sink enemy surface vessels and submarines. However, the attack type is the most effective. Specialized attack types called hunter-killer submarines are designed to destroy other submarines. Guided missiles make submarines effective against shore targets and more dangerous than ever before to shipping and naval vessels. Some submarines are designed to launch ballistic missiles with nuclear warheads; no point on earth is beyond the range of these missiles.

A number of important secondary uses for submarines developed during World War II. Submarines carried ammunition and supplies to ports that were surrounded by the enemy. The U.S. Navy submarine Trout brought out gold, silver, and valuable securities from the Philippines. Soldiers were sometimes sent ashore from submarines for surprise raids, and submarines were used extensively to rescue downed aviators.

In sea warfare, a submarine attempts to avoid detection while getting within effective torpedo range of enemy ships. The main purpose of the U.S. Navy's ballistic-missile submarines is to make it unprofitable for an enemy to launch a surprise nuclear attack. By constantly moving about while remaining within range of their targets, such submarines make it virtually impossible for an aggressor to destroy all of the United States' means of launching a nuclear counterattack.