During World War II, a massive airborne mine-laying operation destroyed 650 Japanese ships, choking the Japanese industrial complex and making a U.S. victory unavoidable. An airborne mine-laying operation also marked the end of the Vietnam war.
In the 1970s, the U.S. developed a sea mine that was basically a torpedo encapsulated inside an aluminum tube. The mine is called the Mark 60, also known as the CAPTOR (enCAPsulated TORpedo mine). These mines can be dropped from a ship, parachuted from an airplane or pushed out of the torpedo tube of a submarine. Once it hits the ocean, the CAPTOR deploys a mooring weight attached to it by a tether, allowing it to stay moored at a depth of 2,000 feet. The capsule would then start listening for the unique seismic signatures of an enemy submarine or surface ship. When it sensed an enemy vessel passing overhead, the torpedo would leave its tube and home in on the enemy vessel before detonating.
No one knows what happened to the CAPTOR mine. Indications are that the U.S. stopped ordering them in 1986. If they’re still in use, their status must be top secret, as sea-mine experts don’t mention them in the present tense anymore.
The only U.S. sea mines mentioned these days are submarine-launched mobile mines (SLMMs) and “Quickstrike” airplane-dropped mines. Quickstrike mines are basically conventional air-dropped bombs that had their fuses replaced with seismic sensors similar to those of the CAPTOR. These would be dropped by airplanes into shallow water, where they’ll simply sink to the ocean floor. If they sense an enemy vessel, they go kaboom. The tails of these “Quickstrike mine” bombs have also been replaced with JDAM guidance packages, allowing them to be dropped from high-flying planes and placed with precision. Another development was to add wings to some of these re-fused guided bombs. These wings pop out after the Quickstrike mine is dropped, allowing it to glide more than 40 miles to its final destination.
There are also rumors of programs to add capabilities to U.S. mines. One of these is to add a propulsion system like a rocket or jet engine or propeller engine to an air-gliding Quickstrike mine so as to turn it into a sort of “cruise missile sea mine.” Such a system would be able to fly much farther, thereby greatly increasing the distance between the aircraft and the mine’s final destination. This increased stand-off distance is very important, as traditional aircraft-based mine-laying is a very dangerous job, requiring planes to fly low and slow over the mine-laying area, which is usually in enemy territory and therefore covered by anti-aircraft weapons.
The SLMM is a torpedo-based mine that is designed to be deployed covertly by submarines in shallow waters. Unlike the CAPTOR, the SLMM is not a deep-water mine and does not have a capsule. It is more like a “patient torpedo” that lies naked on the ocean floor and listens out for passing vessels. New systems that are similar to the CAPTOR and SLMM are being developed, but there is not much new info on these developments.
Laying naval minefields via aircraft is preferable because airplanes can lay more mines and do it faster than submarines and ships. However, a good example of how dangerous it can be to lay mines via aircraft was illustrated in 1991 during the Iraq War. On January 17, 1991, a group of U.S. A-6 Intruders were sent to drop Vietnam-era naval mines in a narrow part of the Euphrates river. The Intruders took off from aircraft carriers just after sunset and dropped down to minimum altitude as they crossed over the mouth of the Euphrates. Around them, tracers and shells filled the air above them as Iraqi AAA batteries opened up on them. As the Intruder force started dropping their mines, one of the Intruders was hit and exploded, killing the crew of two. This would be the last time the U.S. engaged in airborne mine-laying during a conflict.
U.S. analysts are complaining that too little is being done to improve U.S. mine technology, and too few advanced mines are being produced. They point at the enormous success of sea mines when U.S. aircraft dropped over 12,000 such mines into Japanese shipping routes and harbor approaches during World War II. These mines sank 650 Japanese ships — more than all other weapons combined — and seriously disrupted Japan’s maritime shipping. Surely it is time to reconsider the importance of the sea mine?
The U.S. only used air-dropped sea mines twice after the Second World War. The second and last time was when that Intruder was destroyed in Iraq. The only other time was at the end of the Vietnam War, when U.S. Navy A-6 Intruders dropped sea mines in the waters of North Vietnam’s Haiphong harbor. As the mines were being dropped, U.S. President Nixon announced the act in a televised statement. Nixon explained that the mines would only become active after 72 hours, thereby allowing ships from other nations three days to escape. Nixon said the U.S. would clear the minefield once Vietnam had released 600 U.S. prisoners of war suffering in its prison camps. The U.S. then started to clear the minefield as Vietnam started to release the prisoners. When Vietnam stalled the release process, the U.S. simply stalled the mine-clearing process. In the end, the prisoners were released and the U.S. cleared all the mines it had laid.
The incident showed the true value of naval minefields. By international law, these minefields have to be declared publicly once they have been laid, and then the onus is on the enemy if it wants to keep using the mined harbor or sea lane and get hurt, or stop using the area. The idea was not so much to sink enemy warships or cargo ships, the idea was to force the enemy to stop using a vital part of its waters and thereby crippling the enemy’s industrial and weapons supply. In the case of Haiphong harbor, the sea-mine plan worked perfectly. Not one ship was damaged, but the temporary minefield strangled North Vietnam’s shipping and put massive pressure on Hanoi’s economy.
If China decides to invade Taiwan, it would be vital for either Taiwan or the U.S. to be able to create naval minefields on short notice. The problem is of course that laying a minefield in another nation’s waters is an act of war, so it would make sense for Taiwan to have its own mine-laying capacity. Taiwan is currently creating a mine-laying force that is focused on quickly creating defensive minefields around its harbors and invasion-friendly beaches. Its navy has already received some of the Taiwan-built minelayer ships and mining-capable corvettes it had ordered in 2019.
These ships are all fitted with rails and automatic mechanisms that enable their crews to lay defensive minefields quickly. However, analysts were taken aback when publicity photos of a mine-laying exercise in June of this year showed that at least one of the new ships was practicing with the training version of a U.S.-made Mark 6 mine — a mine that was first designed in 1917 and extensively used in WWII. Taiwan did ask the U.S. in 2018 if it could buy some of its modern Quickstrike aircraft-laid mines, but negotiations seemed to have gone nowhere.
Analysts say that there is a real risk that China will launch a preemptive strike on U.S. forces in the Pacific as the first part of its attack on Taiwan. Calculations show that, with a bit of luck on China’s side, U.S. forces in the Pacific can be severely damaged and pushed far back from Taiwan — left with few weapons capable of reaching into the Taiwan Strait. As naval mines like the Quickstrike are relatively cheap to manufacture, and as their effect on China’s harbors and commercial shipping would be massive, analysts suggest that the U.S. should start to invest heavily in quickly producing many of these devices. Such a move would go a long way toward rebalancing the power imbalance that has been growing in China’s favor over the last 20 years.
By spending relatively little on sea mines, the U.S. would be able to severely damage China’s ability to import the oil and other raw materials that its economy depends on so very much. If it could deploy large numbers of SLMM and Quickstrike mines to Chinese shipping lanes and harbor approaches, the effect would be devastating, and it might even be able to trap large numbers of Chinese warships inside their harbors.
The only problem would be for U.S. aircraft to get close enough to China’s coastline to deploy the mines accurately. This can be remedied by creating minefields far away from China, at the few vital chokepoints where all China’s incoming and outgoing cargo ships have to pass through narrow waterways.
New versions of the Quickstrike mine can also be created by simply slapping on a propulsion system on the back of a gliding Quickstrike. Such a powered naval mine would be able to fly long distances before shedding its wings and engine, using its GPS-guided JDAM tail section to guide it to its precise destination as it falls back to Earth. Such devices can be launched from U.S. bombers or even fired from U.S. warships. If the U.S. could allow itself to sell these to Taiwan, they can be launched from Taiwanese soil without the need to put U.S. warships or airplanes at risk.
In conclusion, there are huge advantages to creating minefields in the approaches to China’s harbors and in its shipping lanes. Such minefields could cripple China’s economy and a big part of its war machine, and the mines themselves would be relatively inexpensive to manufacture. For these reasons the U.S. needs to urgently look at ways to increase the stand-off range of its Quickstrike precision mines, and also work with Taiwan to find ways to deliver such mines to China’s back door. A “Pearl Harbor event” always happens before anyone expects it, and it might happen sooner than later, so a sense of urgency is required here.
Image: U.S. Navy