RUM-139 Vertical Launch ASROC

A surface-to-underwater missile that can be fired from the vertical launch system of U.S. Navy and compatible warships, carrying a standard lightweight homing torpedo up to 28 km/15 nmi to the target area. Once the target area is reached, the rocket booster drops a standard Mark 46 or Mark 54 antisubmarine torpedo, the same as used by maritime patrol aircraft such as the P-3 Orion and P-8 Poseidon, or antisubmarine helicopters of the H-60 family.

Airdropped torpedoes remain the primary U.S. Navy antisubmarine weapon, but ASROC gives a capabilility either to supplement the weapons aboard an aircraft, to engage a target detected by a submarine without revealing the submarine's presence, or to prosecute a distant target located by shipboard sensors.

In Russian service, the RPK-2 Viyuga (NATO designation SS-N-15 STARFISH) is a comparable weapon.

While the need for such a weapon seemed to diminish with the end of the Cold War, new applications have emerged, where it might be used to engage a submarine in territorial waters of an adversary, without the risk of sending a manned vehicle into them.