Covert Shores reports on Iran’s version of an unusual asymmetric threat that originated in North Korea. Used by the Islamic Revolutionary Guard Corps, PATFORSWA may encounter these.

“I originally interpreted these to be Special Operations assets intended as a form of swimmer delivery vehicle. This would be consistent with related types in North Korean and Vietnamese service. In that role the torpedoes would be for self-defense. However, I now view them more as submersible torpedo boats intended to sink ships with torpedoes.”

The torpedoes are 12.75 inch (324mm) light weight anti-surface homing torpedoes. (243mm noted in the diagram above is apparently a typo.) We can’t take too much comfort in the fact that these are not heavy weight torpedoes. Heavy weight torpedoes frequently break ships in half, but because water is not compressible, the 100 pound warhead of a typical light weight torpedo still has about one half the impact of the 600 pound warhead of a typical heavy weight torpedo. These smaller torpedoes can seriously hurt even a large ship, possibly including immobilizing it, and making it an easier target for follow on attacks. Used against a vessel the size of PATFORSWA’s Fast Response Cutters, they would be fatal. Assuming these are wake homers, it might be wise to learn the maneuvers used to defeat wake homing torpedoes.

It is unlikely these little submersibles can go very deep or that they have much mobility while submerged. Even so, much of the Persian Gulf is shallow, so there are certainly places where they could rest on the bottom, lying in wait.