Naval Mines

A naval mine (sea mine) is an explosive device placed in the water that blows up when a ship comes into contact with it or comes near it. Unlike a torpedo or a missile, a mine does not chase its target; it waits. Mines are cheap, easy to lay and very hard to find, so even a weak navy can use them to block a port or a narrow sea route. That is why they are called "the weapon that waits".

Why do countries use mines?

A mine works like a hidden landmine on a road. You do not need to sink many ships; the fear that a mine might be there is often enough to stop traffic. Shipping companies avoid the area, insurance costs jump, and navies must spend weeks clearing the water. For a country that cannot match a bigger navy ship for ship, mines give a cheap way to deny the use of the sea.

Military writers call this sea denial, which means stopping an enemy from using the sea, as different from sea control, which means using the sea yourself.

Where did they come from?

Early floating explosive devices were used in the American War of Independence and later wars in the 1700s and 1800s. Mines became a major weapon in the Russo-Japanese War (1904-05), when they sank battleships on both sides. After that war, countries agreed on the Hague Convention VIII (1907) on automatic submarine contact mines. In the First and Second World Wars, hundreds of thousands of mines were laid, for example the North Sea Mine Barrage of 1918.

In the 1980s Iran-Iraq "Tanker War", the reflagged tanker Bridgeton hit a mine in July 1987 while under US escort, and the US frigate USS Samuel B. Roberts struck an Iranian mine on 14 April 1988. Four days later, on 18 April 1988, the US Navy hit back with Operation Praying Mantis. In the 1991 Gulf War, Iraqi mines damaged two US warships, including the cruiser USS Princeton.

How do mines work? The main types

• By position:
• Moored mines: float under the surface, tied by a cable to an anchor on the seabed.
• Bottom (ground) mines: lie on the seabed in shallow water.
• Drifting mines: float freely with the current. These are the most dangerous for neutral ships, which is why the 1907 Convention restricted them.
• Limpet mines: stuck to a ship's hull by hand, usually by divers, using magnets.
• By how they are triggered:
• Contact mines: explode when a ship physically touches them (the classic mine with spikes, called "horns").
• Influence mines: have sensors and explode when they detect a ship's magnetic field (from its steel hull), its acoustic signature (engine and propeller noise) or a pressure change in the water as it passes. Some use two or three sensors together.
• Controlled mines: set off by an operator on shore, by cable or remote signal.
• Modern mines can count ships and let the first few pass, which makes clearing them even harder.

How are mines cleared? (Mine countermeasures)

• Minesweeping: a ship drags a cable to cut moored mines loose, or tows devices that copy a ship's magnetic field or noise so that influence mines explode harmlessly. It is fast but not complete.
• Minehunting: ships use sonar (sound waves) to find each mine, then divers, remotely operated underwater vehicles or small charges destroy it. It is slow but more thorough.
• Navies now also use helicopters and unmanned underwater drones for this work.
• Mine countermeasure ships are often made of wood, glass-reinforced plastic or special low-magnetic steel so that they do not set off magnetic mines themselves.

What does international law say?

• Hague Convention VIII (1907) is still the only treaty specifically about naval mines. It bans unanchored contact mines unless they become harmless within one hour after the person who laid them loses control of them. It bans anchored mines that do not become harmless once they break loose. It bans laying contact mines off an enemy's coasts and ports with the sole aim of stopping commercial shipping. It requires every possible care for the safety of peaceful shipping, and notice of danger zones as soon as military needs permit.
• The Corfu Channel case was the first judgment of the International Court of Justice (ICJ) on 9 April 1949. Two British destroyers hit mines in Albanian waters on 22 October 1946. The Court held Albania responsible because it knew about the mines and did not warn ships. It also confirmed the right of passage through international straits.
• The San Remo Manual (1994), a non-binding expert guide on the law of war at sea, also says that mines must not block passage between neutral waters and international waters.

India's position

The Indian Navy's mine countermeasure fleet was built around minesweepers bought from the Soviet Union in the late 1970s, which were retired by about 2018-2020. A plan to build 12 mine countermeasure vessels at Goa Shipyard with a South Korean partner was cancelled around 2018. The Navy has said it needs about 24 such vessels.

On 3 July 2025, the Defence Acquisition Council gave initial approval (Acceptance of Necessity, the first step in defence buying) for 12 mine countermeasure vessels to be sourced from Indian industry, at an estimated cost of about ₹44,000 crore. It also approved moored mines for the Navy at the same meeting. Since most of India's oil comes by sea through chokepoints like Hormuz, mine threats directly affect India's energy security.

The Indian Navy has run escort missions (such as Operation Sankalp, started in 2019) to protect Indian-flagged ships in the Gulf region.

Commonly confused concepts

• Mine vs torpedo: A mine waits in one place. A torpedo is a self-propelled underwater weapon fired at a target.
• Minesweeping vs minehunting: Sweeping clears an area without finding each mine. Hunting finds and destroys mines one by one.
• Naval mine vs mineral mine: "Mine" here is a weapon, not a place where coal or iron ore is dug. Laws like the MMDR Act, 1957 are about mineral mines, not sea mines.
• Blockade vs mining: A blockade is when warships stop ships from entering or leaving ports. Mining is placing explosives in the water. Both deny the use of the sea, but in different ways.

Issues, criticism and the way forward

• Danger to neutral ships and civilians: Mines cannot tell a warship from an oil tanker or a fishing boat. They can keep killing long after a war ends.
• Old and weak law: The 1907 Convention was written for simple contact mines. It says little about modern influence mines and smart mines.
• Environmental risk: A mined tanker can spill oil, damaging coral reefs, fisheries and coasts in a narrow sea like the Gulf.
• Clearance capacity: Many navies, including India's, have too few modern mine countermeasure vessels.
• Way forward: Experts suggest updating international rules on modern mines, sharing mine maps after conflicts, investing in drone-based mine hunting, and building national mine countermeasure fleets.

Concepts to Know

• Chokepoint: A narrow sea passage that many ships must use, so blocking it affects a large share of world trade.
• Sonar: A system that sends out sound waves under water and listens for echoes to find objects.
• Reflagging: Registering a ship under another country's flag, often so that it can get that country's naval protection.
• Escort: Warships sailing alongside merchant ships to protect them.
• Customary international law: Rules that become binding on all countries because they have followed them for a long time and believe they are required by law, even without a written treaty.