The U.S. Navy took a step towards a new style of warfare this week with a request for proposals for its new Hammerhead Program. The Navy is looking for contractors to supply a mine that can be placed covertly on the sea bed by a robot submarine; when Hammerhead’s sensors spot a target, it fires an encapsulated homing torpedo.

Hammerhead procurement is being fast-tracked, under both a Navy Maritime Accelerated Acquisition initiative and an Acquisition Rapid Prototyping Program. The mine is needed urgently because it forms a key part of the National Defense Strategy for peer naval competition. The Strategy may not put it so bluntly, but the challenge is countering submarines on their home turf in the South China Sea. Hammerhead is first and foremost an autonomous anti-submarine weapon that can be widely deployed in large numbers.

Hammerhead consists of several modules. The mooring module keeps it tethered to the sea bed; the energy module provides power, and the sensing module is a sonar device to detect nearby vessels. Then there is the weapon element, a modified version of the veteran Mark 54 Lightweight torpedo. This is a 600-pound weapon with a range of at least six miles widely used by the U.S. Navy and others for anti-submarine operations. (Anti-ship torpedoes are several times larger).

The ‘Command, Control, Signal Processing and Decision Making module’ will presumably be responsible for deciding whether or not to fire at a specific target. While autonomous weapons are an issue elsewhere, naval mines have always been effectively autonomous.

Significantly, Hammerhead also has a communications module. This will likely be based on an acoustic modem, for communication with nearby submarines, sensors and possibly other Hammerheads. This will make it possible to activate or deactivate Hammerhead after it had been put in position.

The U.S. Navy previously operated a less sophisticated encapsulated torpedo. During the Cold War, the U.S. Navy acquired large numbers of Mark 60 CAPTOR (as in enCAPsulated TORpedo) mines, based on the old Mark 46 torpedo. Produced in the 1970s and ’80s, the plan was to drop CAPTORS from the air and close off the Greenland-Iceland-UK gap to Soviet submarines with an underwater minefield. CAPTOR was taken out of service in 2001 when it was no longer required.

The new Hammerhead differs from CAPTOR in two important ways. One is that remote control capability, which means it can legally be positioned in peacetime.

“Since it is not expressly forbidden to place unarmed mines in international waters, modern mines with a remote-control capability could be deployed at any time provided their detonating mechanism was turned off. This would provide offensive mining with the flexibility of controlling the movement of enemy submarines in times of tension,” according to a 1997 study by the Institute for Defense Analysis.

The other difference is that Hammerhead is explicitly intended to be surreptitiously placed underwater rather than dropped from the air. Minefields can be placed in strategic choke points or outside submarine bases without anyone being aware.

Capt. Chris Merwin of the Naval Surface and Mine Warfighting Development Center told an NDIA conference last year that mine warfare was about to change “big time.”

“There are a lot of systems, Future Naval Capabilities, that are being tested,” said Merwin. “The future of mining will be clandestinely launched mines. And that’s probably as much as I can say.”

While such mines could be delivered by manned submarines, these are scarce and expensive assets. The focus is on delivering them with a new generation of large, long-range Unmanned Underwater Vehicles (UUV), in particular the Orca Extra Large UUV in scheduled to be in service for 2022 and the Snakehead Large Diameter UUV in 2023.

Unmanned Undersea Vehicles Squadron One (UUVRON-1) is already developing its tactics and procedures in Washington State, with two test vehicles which simulate Snakeheads, and they are preparing to start using an XLUUV prototype 

The squadron have been developing expertise with their robot subs and finding out what they can do, with an emphasis on mining operations, or, as UUVRON-1’s Cmdr. Rob Patchin puts it “We’re going to figure out how to go blow stuff up with the Extra Large.” The Orca XLUUV has a payload of eight tons, giving it the capacity to lay dozens of mines in a single mission.

Such covertly-laid mines could communicate via unmanned Wave Gliders. The U.S. Navy is making increasing use of these small vessels which have unlimited endurance and could provide satellite-to-underwater communications link to a Hammerhead minefield, as well as additional submarine-tracking sensors. The beauty is that all of it – the mine-laying drone submarines, unmanned surface vessels and even the Hammerheads themselves – can be operated remotely, and even deniably.

The future of mine warfare may look like aerial drone warfare today: carried out remotely with unmanned systems, satellite communications and sophisticated sensors. It is easy to forget that in WWII, mines sank more ships than guns, torpedoes or bombs. With the advent of weapons like Hammerhead, we may see a similar pattern going forward.