An Act of War? The Law of Naval Mining


A mine is a terrible thing that waits.

The easy way is always mined.

But it might not be an “act of war.”


Since the end of World War II, naval mines have seriously damaged or sunk three times as many U.S. Navy warships than any other weapon or means of attack: 15 of 20.

There have been many more ships––either commercial vessels or other countries’ naval ships––damaged or sunk by naval mines, from two Royal Navy surface warships in the 1946 Corfu Channel Crisis, to the Arabian Gulf “tanker war” in the 1980s, to the Tamil Sea Tigers sinking the MV Invincible in 2008. In 1990-1991, Iraq deployed some 1,300 naval mines in the northern Gulf––including a weapon never before seen in the West––which severely damaged two U.S. warships and stymied plans for an amphibious assault east of Kuwait City. The Multinational Coalition post-Desert Storm naval mine cleanup operations took more than two years to ensure waters were mine free. In the summer of 1984, Libya mined the Red Sea and Gulf of Suez with previously unknown Soviet/East German “export” bottom mines, with as many as 23 ships (four of which were more likely insurance “scams”) reporting damage from “underwater explosions.” And, in April 2011, Qaddafi’s naval henchmen managed to get at least three mines into the water off Misrata before he was deposed.

The U.S. Navy and its naval/maritime partners have good reason to be concerned about naval mines, which have been the quintessential “anti-access/area-denial” threat for centuries. “Although the concept of a sea mine can be traced to ‘Greek Fire’ used to defend Constantinople in the year 673,” according to the Navy’s “Mine Warfare Primer” (2009), “in the American experience the first use of mines or ‘torpedoes’ came in an unsuccessful 1776 attack against HMS Eagle in the Hudson River. The first successful U.S. Navy mining occurred during the War of 1812, when mines denied British access to the Port of New York.”

Not counting U.S. stockpiles, there are perhaps a million naval mines of more than 300 types––from relatively unsophisticated but still deadly contact mines to sophisticated multiple-influence weapons––are in the inventories of more than 60 navies. Estimates of Russian naval mine stockpiles run to 250,000 weapons. China’s navy has upwards of 100,000 naval mines. North Korea reportedly has some 50,000 mines and Iran has about 5,000. More than 30 countries produce naval mines and 20 countries export them. Even highly sophisticated, rocket-propelled naval mines are available in the international arms trade. Worse, these figures are for naval mines, proper; they do not include naval IEDs that can be fashioned from 55-gallon drums and other containers––refrigerators and Volkswagens, for example––posing threats to maritime safety and security.

Although probably not “show-stoppers,” naval mines are “speed bumps” that directly hinder strategies, plans and operations. So, there is little wonder that adversary mines and the means to counter them have generated increased interest in the U.S. Navy. (Would it be so as well for the Navy’s naval mines and mining capabilities, but that is the focus of another commentary.)

An Act of War?

In early 2012, tensions between the United States and Iran were spiking, and “mine-rattling” threats from Teheran to close the Arabian Gulf and the Strait of Hormuz exacerbated jittery world petroleum markets. Iranian rhetoric generated increasingly draconian U.S. and UN sanctions. Given the experience of the 1980s “tanker war,” the naval mine threat could not be ignored. On 12 February 2012, Vice Admiral Mark I. Fox, Commander U.S. Fifth Fleet, declared: “If Iran mines the Arabian Gulf, it’ll be an act of war.”

Is this correct? As it turns out, there are international guidelines for naval mining and, if followed, they empower nations to deploy their “weapons that wait” in peacetime and during “armed conflict.” In the latter case, mining by non-state actors, e.g., terrorist groups, might also be permitted.

For example, the Hague Convention VIII of 1907 focuses on “The Laying of Automatic Submarine Contact Mines” (Section VII) during times of war. “Automatic” mines are those weapons not under the direct control of the miner, whether anchored to the sea bottom or not. In 1907, this meant primarily contact weapons (still in many navies’ inventories in 2014), but the rules would also apply to “influence” mines that fire on the magnetic, acoustic, pressure, electric-potential and seismic “signatures” of a target surface ship or submarine. In that regard, Articles 1-2 state, “It is forbidden” to lay:

  • Unanchored (i.e., drifting) automatic contact mines, except when they are so constructed as to become harmless one hour at most after the person who laid them ceases to control them
  • Anchored automatic contact mines which do not become harmless as soon as they have broken loose from their moorings
  • Automatic contact mines, whether anchored or not, off the coast and ports of the enemy, with the sole object of intercepting commercial shipping

Article 3 stipulates that when anchored automatic contact mines are employed, every possible precaution must be taken for the security of peaceful (a broader category than just commercial) shipping. Belligerents must “do their utmost’ to render these mines harmless within a limited time (not just an hour). Furthermore, should these mines cease to be under the miner’s surveillance, the mining countries must notify ship owners and governments through diplomatic channels about the mine danger zones “as soon as military exigencies permit.”

Neutral countries that lay automatic contact mines off their coasts must follow the same rules imposed on belligerents. The neutral state must inform ship owners, by a notice issued in advance, where automatic contact mines have been laid, and this notice must be communicated at once to the governments through diplomatic channels.

At the close of the war, the “Contracting Powers” (i.e., states party to the 1907 convention) must do their utmost to remove the mines that they have laid, with each government responsible for removing its own mines. With regard to anchored automatic contact mines laid by one of the belligerents off the coast of the other, their positions must be notified to the other party by the Power that laid them. For example, after the U.S. Navy mined Haiphong harbor and other North Vietnamese waterways in July 1972 and the Paris Peace Talks resumed in January 1973, U.S. mine countermeasures (MCM) forces were responsible for clearing all mined areas––Operation End Sweep––later that year. As it turned out, most of the naval mines had already been rendered safe through self-sterilization.

And each Power must proceed with the least possible delay to remove the mines in its own waters.

For the U.S. Navy today, the Commander’s Handbook on the Law of Naval Operations outlines the naval mining rules of the road that must be followed, whether during peace, crisis or war, to determine whether deploying “weapons that wait” is a legal action or an act of war.

Section 9.2.2 Peacetime Mining

Mindful of the safety of its citizens, during peacetime a nation may deploy armed and controlled mines in its own internal waters at any time without notification. A nation may also mine its own archipelagic waters and territorial sea during peacetime when necessary for its national security. If a nation deploys armed mines in its archipelagic waters or the territorial sea, appropriate international notification––e.g., through the International Maritime Organization and other diplomatic channels––of the existence and location of such mines is required. However, deploying controlled mines in a nation’s own archipelagic waters or territorial sea is not subject to such notification or removal requirements.

Because the right of innocent passage through territorial seas can be suspended only temporarily, armed mines must be removed or rendered harmless as soon as the security threat that generated their deployment has ended. Armed mines may not be emplaced in international straits or archipelagic sea-lanes during peacetime.

A nation may deploy controlled mines in international waters (i.e., beyond the territorial sea) if they do not unreasonably interfere with other lawful uses of the oceans. The determination of what constitutes an “unreasonable interference” involves a balancing of several factors, including the reason for their emplacement (e.g., self-defense), the extent of the area to be mined, the hazard (if any) to other lawful ocean uses, and the duration of their emplacement. Because controlled mines do not constitute a hazard to navigation, international notice of their emplacement is not required.

The Handbook notes that armed mines may not be deployed in international waters prior to the outbreak of armed conflict, except under the most demanding requirements of individual or collective self-defense. If armed mines were to be deployed in international waters, the deploying nation must provide prior notification of their location. Moreover, a nation deploying armed mines in international waters during peacetime must maintain an on-scene presence in the area to ensure that appropriate warning is provided to ships approaching the mine danger area. All armed mines must be expeditiously removed or rendered harmless, either by sweeping or self-sterilization, when the imminent danger that justified their deployment has passed.

Thus, Gaddafi’s mining of the Red Sea and Gulf of Suez in 1984 could have been regarded as an act of war, but it took about a year to determine, beyond reasonable doubt, that Libyan naval forces were indeed responsible for the mines.

Finally, armed or controlled mines may not be emplaced in internal waters, territorial seas, or archipelagic waters of another nation in peacetime without that nation’s consent.

It is interesting to note that the Handbook here refers only to “nation” and not other non-state actors, e.g., terrorist groups. This must mean that any use of naval mines by non-state actors in peacetime is illegal.

Section 9.2.3 Mining during Armed Conflict

Like the peacetime case, “parties to an armed conflict” may legally employ naval mines, subject to specific restrictions. In this regard, the definition of “parties to an armed conflict” is important as well is “armed conflict”.   The Commander’s Handbook states, “It is the policy of the United States to apply the law of armed conflict to all circumstances in which the armed forces of the United States are engaged in combat operations, regardless of whether such hostilities are declared or otherwise designated as ‘war.’” Thus, a formal declaration of war/hostilities is not a prerequisite for “armed conflict,” and “parties” are not limited to nation states, but can include other non-state actors, e.g., terrorist groups.

With that in mind, the Handbook provides a checklist of requirements for lawful mining by national navies and other parties during armed conflict. If these are not followed, diplomatic as well as kinetic action can be taken against the nation and its miners, their mining platforms and mine stockpiles.

  1. Miners must provide international notification of the location of deployed naval mines as soon as military exigencies permit.
  1. Mines may not be deployed in neutral waters.
  1. Anchored buoyant mines must become harmless as soon as they have broken their moorings.
  1. Unanchored mines not otherwise affixed or embedded on the bottom must become harmless within an hour after the miner’s loss of control over them.
  1. The location of minefields must be carefully recorded to ensure accurate notification and to facilitate subsequent removal, rendering safe in situ or self-sterilization.
  1. Naval mines may be employed to channelize neutral shipping, but not to deny transit passage of international straits or archipelagic sea-lanes passage of archipelagic waters by such shipping.
  1. Naval mines may not be emplaced off the coasts and ports of the enemy with the sole objective of intercepting commercial shipping, but may otherwise be employed in the strategic blockade of enemy ports, coasts, and waterways.
  1. Mining of areas of indefinite extent in international waters is prohibited. However, reasonably limited barred areas may be established by naval mines, provided neutral shipping retains an alternate route around or through such an area with reasonable assurance of safety.

The use of naval mines off Misrata, Libya, late April 2011 serves as a real-world example. The bottom-moored buoyant mines were laid about a mile offshore by pro-Qaddafi naval forces––“parties to an armed conflict”––using inflatable boats. As soon as the minelayers were detected, NATO Maritime Headquarters in Naples warned Misrata port authorities about the threat, and the authorities temporarily closed the facility and cancelled two humanitarian ship movements.

“We have just seen Qaddafi forces floating anti-ship mines outside Misrata harbor,” British Brigadier Rob Weighill, director of NATO operations in Libya. “It again shows his complete disregard for international law and his willingness to attack humanitarian delivery efforts,” he said speaking via teleconference from the operation’s headquarters in Naples.

Italian Navy Vice Admiral Rinaldo Veri, Commander of the Maritime Headquarters for OPERATION UNIFIED PROTECTOR, explained, “The mining of a civilian port by pro-Qadhafi forces [was] clearly designed to disrupt the lawful flow of humanitarian aid to the innocent civilian people of Libya and is another deliberate violation of United Nations Security Council Resolution 1973.”

Within 24 hours of the reported laying of mines, a Royal Navy MCM vessel, the HMS Brocklesby (M33), located and destroyed a mine containing about 250 pounds of high explosives outside of the Misrata harbor. The mines were small and thus very hard to detect but could do serious damage to shipping. Two of the mines were moored to the seabed; however, a third mine drifted free before Brocklesby arrived on scene. (During the Arabian Gulf “tanker war,” for example, the USS Samuel B. Roberts (FFG-58) nearly broke in two and sank after striking a single Iranian SADAF-02 contact mine armed with 253 pounds HE. Estimated to cost (in 1988) about $1,500, the mine caused some $96 million in damages to the frigate.)

The mining was close offshore, well within the Libyan territorial sea and outside internal waters, but governance of the waters was at best uncertain. Still, a cursory assessment is that the pro-Gaddafi “parties to an armed conflict” contravened mandates numbers 1, 3, 4, 5 and 7 in their attempt to mine areas off Misrata, and thus it was an “act of war.” Had this not been the case, and the rules followed, the mining would have been a legal action. In any event, NATO forces targeted Libyan navy mine stockpiles to destroy the threat.

Honored in their Breach!

Perhaps honored more in their breach than observance (as evidenced by Albania’s mining of the Corfu Channel in 1946 and Iran and Iraq’s indiscriminate use of mines during the 1980s “Tanker War”), the laws of naval mining are nonetheless clear. If the rules were followed, in peacetime, crisis and armed conflict, China’s, Russia’s, Iran’s and any other country’s use, including the United States, of naval mines––particularly in self-defense roles––would not, per se, be an “act of war.”

But, that’s a big “if.”

And, given Iranian hyperbole, there’s little wonder that the U.S. Navy and other partners have buttressed their mine countermeasures capabilities in the Arabian Gulf. Just in case.

And, so it might be in the Black Sea, as well. Or in the South China Sea, too.


Dr. Scott C. Truver is director of Gryphon Technologies’ TeamBlue National Security Programs group and is the co-author of the U.S. Naval Institute Press book, Weapons that Wait: Mine Warfare in the U.S. Navy.


Photo credit: Official U.S. Navy Imagery