The United States and Great Britain had deployed nearly 72,000 mines during World War I against Germany to enforce a blockade of the North Sea and to counter the German U-boats. The US deployed nearly 12,000 mines during Operation Starvation in Japanese coastal waters between March and August 1945. These were air-deployable, advanced influence ground mines that were much easier to deploy in offensive mining. Mines have been used in conflicts ranging from Korea, Falklands to Gulf wars and have inflicted major casualties.

The naval mine is a relatively cheap, easy to employ, highly effective weapon that affords weaker navies the ability to oppose larger, more technologically advanced adversaries. The mere existence of mines poses psychological threat to practically stop maritime operations and thus deny access to a desired area at sea. Thus, a mine doesn’t have to actually explode to achieve its mission of access denial. North Koreans were able to deter and delay the arrival of US Marines sufficiently to escape safely, by mining Wonsan Harbour in October of 1950 with about 3,000 mines.

Mine technology has kept a step ahead of the ships designs for low acoustic and magnetic signatures and many countries are engaged in development and production of naval mines. Non-metallic casings, anechoic coatings, modern electronics and finally reasonable costs have made mines a weapon of choice for poor and rich nations alike. It is estimated that about 20 countries export mines while about 30 produce them. Sweden, Russia, China and Italy are the leading exporters. Mine MN 103 Manta from SEI SpA of Italy is one of the most exported mines in the world with about 5,000 Mantas in inventories throughout the world.

Classification, Laying of Mines and Actuation Methods

Mines are classified based upon their depth of operation, methods of deployment or the way they are actuated. The versatility of deployment can be gauged by the fact that mines can be laid by majority of surface craft, submarines, crafts of opportunity and aircraft/helicopters. Mines have been used by countries and non-state actors alike with dangerous effects and thus continue to pose a credible threat to navies as well as merchant marine.

Types of mines are based upon the depth at which they are deployed. As per the US Naval Mine Warfare Plan, the underwater battle space has been divided into five depth zones: deep water (deeper than 300 feet), shallow water (40-300 feet), very shallow water (10-40 feet), the surf zone (from the beach to 10 feet) and the craft landing zone (the actual beach). Mines are of three basic types namely, floating or drifting mines, moored or buoyant mines and bottom or ground mines.

Drifting mines float on surface and are difficult to detect and identify because of factors like visibility, sea state and marine growth, etc. Moored mines are tethered mines using anchoring cables to adjust their depths. These can be contact- or influenced-based mines. Bottom mines are most difficult to locate as they can also get buried under sediment layer which cannot be penetrated by normal sonars.

Mines can be actuated by contact, influence and by remote or a combination thereof. With modular target detection device (TDD) upgrade kits, the older contact mines can be easily upgraded to actuate by influence methods. The influence needed for actuation could be pressure, acoustic or magnetic or a desired combination. In addition, ship counters and anti-mine counter systems are also being incorporated in to the mines to make them much more potent and lethal.

Countering the Threat Posed by Mines

Mine countermeasure operations (MCM) are of offensive and defensive types. While the offensive MCM involves destruction of adversaries’ mines in storage or preventing him from mining the waters, the defensive MCM comes in to play after the mines have been laid. A fundamental constituent for successful MCM operations of both types is actionable intelligence, surveillance and reconnaissance (ISR).

Defensive MCM is further subdivided into active and passive types. The passive type involves minimising ships signatures as well as avoiding mines by accurately localising them. Active MCM on the other hand utilises mine hunting and mine sweeping systems to avoid and/or neutralise the mines and carve out a safe passage for the fleet ships. Neutralisation involves sweeping the water body (with influence or mechanical sweeps) with surface, air or subsurface assets.

Remotely Operated Vehicles

Remotely operated vehicles (ROVs) are the most commonly used vehicles in MCM. ROVs are tethered vehicles connected by an umbilical cable to the mother ship. They offer a mature technology for mine identification and neutralisation. The umbilical provides both power and real time data transmission and control facility.

The PAP system developed by ECA of France is one of the oldest ROVs used in MCM. The current version, PAP Mark 5 with fibre-optic umbilical and 130 kg explosive charge payload capability can operate up to six kts speed, and up to a depth of 300 metres. Some of the other well known systems include the Eagle series of vehicles, developed by Bofors Underwater Systems AB. The Eagle series has the ability to operate in any orientation, including upside down and its extensible manipulator arm is used to place a charge next to a mine while maintaining a safe standoff distance. The newer versions, Double Eagle and Double Eagle Mk II, are much larger, with corresponding increases in depth and speed.

The mine identification and neutralisation (MIN) system has been developed and produced by Alenia Elsag Sistemi Navali and Riva Caizoni of Italy. It can identify and neutralise both moored and bottom mines. Its power pack is a closed-circuit oleo pneumatic accumulator to minimise the noise and magnetic profile. Raytheon’s ROV, AN/SLQ-48(V) mine neutralisation system (MNS), used by the US Navy uses a conventional electro-mechanical cable; the vehicle can reach a speed of six kts, while carrying two cable cutters and a bomblet. Also available is a package that combines bomblet with a cable grabbing capability for the destruction of moored mines. It has a low light TV, high resolution sonar and is manufactured as per military standards.