Traditional navies as well as maritime terrorists can and have used mines and underwater improvised explosive devices (UWIEDs) to challenge military and commercial uses of the seas. Mines have been utilized in defensive capabilities, such as denying access into a region, and offensive capacities, such as denying egress out of a region.
Naval mines are especially potent. On April 14, 1988, a single contact mine nearly sank the USS Samuel B. Roberts (FFG 58), causing over $96 million in damage. Since World War II, mines have seriously damaged or sunk 15 U.S. ships, nearly four times more than all other threats combined.
“In February 1991 the Navy lost command of the sea—the North Arabian Gulf—to more than a thousand mines that had been sown by Iraqi forces. Mines severely damaged two Navy warships, and commanders aborted an amphibious assault for fear of even more casualties,” says a U.S. Navy mine warfare history. However, unlike aircraft carriers and other capital ships, traditional sea mines offer little ability to project power and, once identified, can be avoided.
More than thirty countries produce mines, and twenty countries export them. Iran has reportedly laid several thousand naval mines, North Korea’s 50,000, China 100,000 or so, and Russia estimated quarter-million. Since World War II, sea mines have damaged or sunk four times more U.S. Navy ships than all other means of attack combined, according to a Navy report on mine warfare. There are still an estimated 50,000 mines remaining in the waters from World War I and World War II, Rear Adm. Jens Nykvist, chief of the Royal Swedish Navy, said in a keynote speech at the conference.
With 95% of the world’s commerce moving by sea, the security of waters, coastlines and military personnel remains a key issue for navies. Sea mines and underwater explosives have become cheap to acquire and easy to deploy now pose a real threat to navies and commercial shipping by reducing freedom of movement in shallow waters and strategic choke points.
Similar to the land-based IEDs that devastated North Atlantic Treaty Organization 18 (NATO) forces during operations in Iraq and Afghanistan, terrorists have developed naval mines utilizing commercial-off-the-shelf (COTS) goods integrated with simple influence firing devices. It has become easy for a terrorist to influence the economy by putting explosives in chokes points. A few statically positioned mines would stop all traffic for a long time before it considered safe again.
“There is an increase in the mine threat particularly in the shallow waters of the Baltic Sea,” he said. Some 2,000 to 4,000 boats and ships traverse the sea on a daily basis, which means more targets for mines. The maritime traffic also causes a lot of clutter when trying to detect potential adversaries, he said. There has always been “dynamic tension” in the U.S. Navy between the so-called “blue water Navy” and the “littoral Navy,” DiGiovanni said. But most conflict has taken place in the littorals where ports are located and shipping takes place. That is where sea mines are placed.
Naval mines also have defensive applications and being able to rapidly emplace them could provide an additional layer of defense around strategic naval bases and ports, as well as established or temporary outposts on small islands, during a crisis. In the latter case, they could be useful in deterring immediate enemy amphibious counterattacks and give ground units some extra breathing room to continue establishing a beachhead for follow-on forces.
New Research and development is continuing for new mines and components, including such features as improved capabilities against submarine and surface targets, better resistance against minesweeping and hunting, more flexibility, easier and less expensive maintenance, simpler and faster preparation for laying, and improvement of mine detection and control systems with increased sophistication.
There is also emerging threat of Networked or Swarming mines. The Navy’s Strategic Studies Group 35 concluded the “Navy’s next capital ship will not be a ship. It will be the Network of Humans and Machines, the Navy’s new center of gravity, embodying a superior source of combat power.”
Such a network could consist of networks of sea mine swarms and their support ships. Networked sea mine swarms could converge on masses of adversary ships, bringing to bear overwhelming force. The visibility of surface support ships would enable the network to generate conventional deterrence by signaling the swarm’s presence, while helping maintain the swarm itself.
“Mines are a type of asymmetric warfare. They are cheap. They are easy to place. They’re a nuisance and they are out there,” Frank DiGiovanni, deputy director of the expeditionary warfare division of the U.S. Navy, said at the Undersea Defense Technology symposium in Stockholm, Sweden. They are not just a military problem as they can threaten commercial sea traffic and impede free trade, he noted
There are three important goals to improve counter-mine warfare technology, DiGiovanni said. Navies must improve the speed of clearing mines, the accuracy of their detection systems, and they must reduce the cost of operations, he said.
US Navy planning offensive mine warfare
The U.S. Navy is making an aggressive push toward “offensive” mine warfare designed to attack and destroy enemy ships and submarines with undersea explosives – all while preparing a complex suite of interwoven mine countermeasure technologies. “We will produce a mine warfare plan to include offensive mine lines of effort. We are asking the CNO (Chief of Naval Operations) to sign in the next 90 days,” Maj. Gen. David Coffman, Navy Director of Expeditionary Warfare, told an audience recently at the Surface Naval Association Symposium.
“We are making a strong push toward offensive mining using an undersea capability. We are drawing upon the CNOs wisdom in exploiting what we have strength in. We know we have dominance undersea,” Coffman said. Offensive mine technology will consist of a mixture of more detectable and hidden weapons, each consisting of different combat tactics. “Covert is good and overt is good too. We need a lot of arrows in the quiver because there are different warfighting scenarios,” Coffman said.
At present, the Navy fields the Quickstrike family of air-dropped naval mines and the Submarine-Launched Mobile Mine (SLMM). The U.S. Air Force also employs Quickstrike types on various aircraft, but the program is Navy-managed. The Quickstrike family includes 500-, 1,000-, and 2,000-pound class types, known as the Mk 62, Mk 63, and Mk 64 respectively. Theese converted from Mk 80-series high-explosive bombs and feature a fuzing system that detonates the weapon when it detects an appropriate acoustic, seismic, or pressure signatures from a passing vessel. A fourth type, Mk 65, is another 2,000-pound class Quickstrike mine, but is based on an actual purpose-built mine casing rather than an existing bomb.
Navy has been pursuing two related upgrade programs, known as Quickstrike-J and Quickstrike-ER, for the Mk 80-series members of the Quickstrike family. The first of these simply combines the mine with a GPS-guided Joint Direct Attack Munition (JDAM) guidance package, while the latter adds a pop-out wing kit.
These are game-changing upgrades that allow aircraft to precisely employ the mines from any altitude and, in the case of the -ER types, loft them at targets up to 40 miles away. This speeds up the process of laying the minefields overall and dramatically reduces the vulnerability to the aircraft carrying the weapons, which would otherwise have to fly low-and-slow to perform the mission.
US Navy has developed a new weapon the stand-off mine or glide mine.It is a hybrid weapon, a combination of a Quickstrike mine and JDAM, or Joint Direct Attack Munition, that attaches fins and GPS guidance to conventional “dumb” bombs, thus turning them into cheap guided bombs. This Quickstrike mine had been fitted with JSAM-ER, which slips actual wings on to the weapons, enabling it to glide long distances. The new weapon, designated GBU-62B(V-1)/B Quickstrike-ER, has a range of 40 nautical miles when launched from 35,000 feet. High-altitude glide mines also allow aircrews to drop their loads much farther outside enemy air defenses.
A very different type of weapon from the Quickstrike mines, CAPTOR consisted of a Mk 46 lightweight torpedo inside a launch canister. After hitting the water, an anchor would deploy, holding it in place at depths up to 2,000 feet. The weapon had a Reliable Acoustic Path (RAP) passive sonar targeting system that could discriminate between hostile submarines and surface vessels and friendly submarines that might also be operating in the area. Once it detected an enemy target, it would fire the torpedo, which would then use its own guidance package to home in on the opponent. The Mk 67 SLMM, which is still in service, is of the basic design, but gets shot out of a submarine’s torpedo tube.
The Navy’s Hammerhead program plans to leverage the older CAPTOR’s basic casing and air-drop components, such as the lugs to attach it to an aircraft. However, the new weapons will have improved targeting sensors, electronics, and software, along with better batteries to power the upgraded systems. The mine will also have a modular design and use open-architecture software with an eye toward adding in new and improved detection and other capabilities in the future. Depending on the improvements made to the batteries in Hammerhead, the weapon could potentially lie in wait even longer than the CAPTOR, which could remain active for months
Separately, the Navy is developing a new mine that both submarines and future large unmanned undersea vehicles will be able to employ, known as the Clandestine Delivered Mine (CDM).
U.S. Air Force Col. Michael Pietrucha in an article in Air & Space Power Journal. Pietrucha paints several scenarios where U.S. glide mines could have a major impact. “Headquarters People’s Liberation Army Navy fleet at Zhanjiang, Ningbo (Zhoushan), and Qingdao are all susceptible to interdiction, with Zhoushan the easiest to isolate and Ningbo the most difficult. The fleet’s submarine pens on Hainan Island have limited approaches and might be bottled up from standoff range. A sunken ship in a shipping channel can prove brutally effective.”
Pietrucha raises the intriguing possibility of using JDAM ER/Quickstrike to place instant defensive minefields in the face of an enemy amphibious assault. Should Beijing attempt to seize Taiwan or disputed Pacific islands, minefields could easily disrupt the landings. Pietrucha also suggests the next logical step, which is adding an engine to the Quickstrike ER/JDAM and thus creating a mine-missile with a range of hundreds of miles.
Mine warheads use underwater blast to inflict damage on the target ship or submarine. The damage energy transmitted is approximately equally divided between the initial shock wave and the expanding gas bubble. If the target is straddling the gas bubble, then it will have unequal support and may be broken in two. As the detonation depth increases, particularly in excess of 180 feet, the effect of the gas bubble causing damage is greatly diminished; there-fore, bottom mines are rarely used in waters exceeding 180-200 feet.
Sea mines range from cheap, simple explosive devices which many fear may fall in the hands of terrorists, to sophisticated computerized systems equipped with sensors and designed to wait hidden on the sea bed for years until the right target presents itself. They are fitted with acoustic, magnetic, seismic, and pressure sensors, which can pinpoint the size and shape of a ship moving in water and detect ship’s approach.
Position in the water column
Mines are classified according to three characteristics. The first characteristic is its position in the water column. Bottom mines, which can also include buried mines, are generally found in shallow water, where either surface craft or submarines can easily trigger them. The advent of the bottom or buried mine shifted the paradigm in mine warfare because mines no longer had to sacrifice space to allow for buoyancy volume, but could instead be filled completely with explosives. This made for more destructive mines in smaller packages
Moored mines (also called tethered mines) are usually used in deeper water and can be positioned at any depth in the water column. Moored mines are highly effective against both ships and submarines. Drifting mines move with the prevailing current direction and are designed to float at or just below the sea surface. Surface mines are either moored (via a chain to the bottom) or floating (a favorite terrorist tactic), and many float just below the surface.
Method of Delivery
The second characteristic is its method of delivery (although most mines can be altered for a different mode of delivery). Aircraft-laid mines are generally used for offensive actions where mines need to be rapidly deployed. These mines are dropped like bombs from an aircraft. Surface laid mines can be deployed from a variety of ships, enabling them to be laid secretively. Submarine-laid mines are designed to be fired out of torpedo tubes and thus, these types of mines are often torpedo shaped.
Controlled mines are triggered remotely, using cables connected to shore, although new designs can be remotely controlled, which will effectively allow a minefield to be turned on and off when needed to allow ships to pass through the mined area. This type of mine is typically used defensively and is particularly effective in preventing entrance to straits or confined areas.
Method of activation
The third characteristic is its method of activation. Contact mines are the oldest technology for mine activation and, in the simplest version, are designed to detonate when “horn” on the mine is bent. Contact mines are the most inexpensive to acquire, are highly reliable, and are extremely effective, which is why they have been highly proliferated throughout the world. These mines utilize several contact “horns” that contain a glass vessel filled with an electrolyte solution, that, when broken, such as when a ship contacts the mine, will create the electric current necessary to detonate the mine.
Influence activation is the most common method. Detectors are used to sense changes in fluid pressure or acoustic, magnetic, and electric fields (or a combination of all four). Sensors can be designed to distinguish between different types of vessels or to have delays before detonating to ensure maximum damage to the triggering vessel.
“A magnetic influence mechanism is a device that is designed to sense a change in the earth’s ambient magnetic field that is caused by a target ship.”
“Acoustic influence mechanisms consist basically of passive microphones and associated circuitry for detecting underwater noises and active transponders that transmit signals and receive echoes from a previously acquired target. The passive mechanisms consist of hydrophones that are responsive to the characteristic frequency, intensity, and duration of detected noises generated by a ship’s propeller, engine, machinery, or hull noises.”
“Pressure influence mechanisms detect the low-pressure zone created beneath a moving ship’s hull. This system may be affected by surface wave action, and, as a result, it is used primarily in sheltered waters only in combination with another influence mechanism.
“Combination influence mines consist of acoustic, magnetic, and pressure-firing mechanisms assembled together, each of which is responsive to its own type of influence. Each sensing mechanism must receive the appropriate signal in a specified period of time for the mine to detonate.
A customary practice for influence mines is ship counting, ensuring that the mine will not actuate on the lead ship of a convoy. Ideally, this arrangement will wait until a ship of higher value, like an aircraft carrier, enters the mine field before actuating. The other advancement that followed influence technology was the exploitation of the bubble jet effect. Bottom mines explode on the bottom and create a giant bubble some distance below the ship that eventually erupts into the air (Worldwide Independent Inventors Association 2009). If the column of water, created by the bubble prior to eruption, contacts a ship, it can easily puncture a meter-wide hole through the skin of the ship.
Mines are getting stealthy, smart and lethal
They have become stealthier by minimizing their sonar profiles, smarter in distinguishing targets from decoys and evolved into lethal systems that can fire torpedoes. With advances in materials technology mines can be rendered near invisible to many forms of detection, can have sweep resistance, dummy mines can be laid (barrels of concrete as an example), smaller explosives can cut sweeper chains, and so on.
Referred to as mine stealth, some mine manufacturers have developed mines that encourage sea growth on the exterior shell as well as utilize irregular exterior shapes to improve camouflage with the sea floor. These aspects of bottom and buried mines pose one of the most challenging threats in the mine warfare domain
Also in the influence mine family is the ascending, or propelled, mine. In the 1960s, the Russians developed a new type of mine that operated in deep water (up to 400 meters), detected a ship overhead, and propelled itself upward towards the target .
The Russian MDS-1 warhead was based on a production torpedo used during that time. These mines were typically deployed covertly from a submarine platform. They utilized passive sensors to detect vessels overhead, and activated acoustic sonar that fed the rocket or torpedo with target data. The mine then launched its torpedo or rocket towards the target. Homing type mine tracks to a target instead of simply propelling itself towards the surface. These mines come in a variety of configurations including straight rising, aimed, and homing.
Captor mines have also been developed that actually launch a smart torpedo that then passively and actively homes in on the target before detonation. Torpedo warheads must be capable of damaging both ships and submarines
There are modern smart mines that can target specific ship types. Many modern mines are also highly resistant to sweeping, due to their intelligent fuses that can detect when someone is attempting to purposely trigger the acoustic, magnetic, or pressure sensors. Some rocket-propelled warheads may even be able to target low-flying aircraft, like say a mine hunting helicopter.
A final consideration for influence mines is the requirement for power. Unlike the contact mine, influence mines require electric power to operate their sensors. To remain active for months or even years, power conservation is significantly important to these devices. Most of these mines operate in a semi-dormant state, relying on an unpowered or low-powered sensor to activate them. Currently, primary batteries with lithium thionyl chloride or silver-zinc chemistries are the standard battery source for these mines.
Networked mine fields or Swarming Sea Mines
Another aspect that must be considered when addressing influence mines is the potential for networked mine fields. On the emerging side of naval mine technology, mine field architectures have begun to incorporate networks of mines connected to each other to distribute sensors and develop even more sophisticated mine fields.
Enabled by acoustic communications (ACOMMS), these mine fields will increase the advantage of the miner by improving their ability to identify friend or foe and pass information about the location, heading, and speed of approaching ships to other mines in the field.
These mine networks will also be able to coordinate efforts via cooperation from groups of mines to inflict the most damage upon the adversary. Interconnectivity could also enable networks of sea mine swarms to coordinate strikes, significantly increasing the number of attack drones. Such a capability would be useful in attacking an adversary fleet, with multiple swarms coordinating target selection.
Multiple attack drones may launch attacks from different directions. This increases the likelihood of successfully sinking an adversary ship because (1) strikes hit different parts of the adversary hull and (2) it enables multiple strikes on the same target, putting at risk larger ships that may survive a single detonation. However, swarming sea mines can play additional roles, such as protecting friendly vessels.
Maneuverability enhances the psychological effects of minefields. Once a vessel passes through a traditional minefield, it is often safe. However, a swarming minefield may move to a new area, adding new uncertainties.
Greater maneuverability enables drone-based naval mines to incorporate automated retreat rules. For example, after a specified time, drones may disarm and leave the area. Friendly vessels may then retrieve and redeploy them in another location. Maneuverability and information integration would enable swarming sea mines to greatly increase the threatened area. Sensor drones can disperse broadly to provide maximum situational awareness.
In theory, a sea mine swarm could consist of tens of thousands of interconnected mines, able to overwhelm any target. The primary limitation on swarm growth is the capacity to manage the rapidly increasing complexity of drone information exchange.
There are also rumors of nuclear armed mines in the inventories of China and North Korea. They have potential to become surprise weapon in any future war. Indeed, sea mines are key to regional navies’ anti-access/area-denial (A2/AD) and sea-control strategies and operations.