A Navy briefing slide showing the internal components and describing the various features of the PSU_ARL Common Very Light Weight Torpedo (CVLWT) design

The January 2025 US Naval Institute Proceedings includes an article suggesting the development of “Propulsion Disablers.”

A propulsion disabler (PD) is a small, passive, torpedo-like device that serves as a cheap, non-lethal mine and torpedo warhead. The proposed munition’s purpose is to destroy a ship’s external propulsion or direction-control mechanisms, leaving the vessel stationary. Production of PDs is possible with today’s emerging robotics technologies. Future PD devices could be used in an autonomous swarm that combines the smallest explosive charge with the greatest disabling effect by attacking a ship at its most vulnerable point.

I have been advocating for a propulsion disabler (ship stopper) since at least 2011, since Coast Guard missions imply a requirement to be able to forcibly stop any ship, regardless of size. This article is the first I have seen that suggests the Navy may see a need for a similar weapon.

The Very Light Weight Torpedo pictured above appears to be a likely basis for a propulsion disabler.

One potential scenario where this capability might be required is in the case of an effort to impose a blockade. The linked post discusses this in relationship to a blockade of China.

The propulsion disabler concept first emerged in the search to make a Western blockade strategy affordable and sustainable, and to solve the moral, political, and legal problems involved in a blockade

Another US Naval Institute article explains the problems that might be encountered in the imposition of a blockade,

Legally, deliberately targeting neutral merchants and civilians would be an excellent way to get hauled before the International Court of Justice at the Hague while alienating not only the neutral state but also the home nations of the crew. Ethically, it constitutes a direct attack on civilians. Tactically, attacking and sinking merchantmen would involve the expenditure of an unacceptable number of heavyweight torpedoes or advanced antiship cruise missiles (ASCM) better employed against high-end enemy combatants or troop transports. The economic damage to fisheries caused by the sinking of a single supertanker would devastate coastal nations. Strategically, it could turn neutral-friendly nations into neutral-hostile nations.

The second USNI article makes no mention of Coast Guard assets in the execution of a blockade of China, but that does seem like a likely mission for Coast Guard units and special teams.