Global Submarine Proliferation: Emerging Trends and Problems

Global Submarine Proliferation: Emerging Trends and Problems

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James Clay Moltz

Deputy Director, The James Martin Center for Nonproliferation Studies

For information on the submarine programs of individual countries, please see the Submarine Proliferation Database.


The end of the Cold War has had both positive and negative effects on the global proliferation of submarines. On the one hand, the overall number of submarines active in the world's oceans is down, due to the precipitous decline in the Soviet/Russian fleet since the end of the Cold War. Nearly 200 former Soviet nuclear submarines have been decommissioned because of a lack of Russian funding for their crews, operations, and required maintenance. Many other countries have also slowed their procurement programs in response to the Cold War's end. However, regional tensions continue to flare in various parts of the world, driving submarine procurement by a number of other navies. As one analyst summarizes: "A multi-billion dollar undersea arms race is gathering momentum as established powers and smaller nations rush to build or buy potent submarines."[1] But perhaps most troubling of all is the fact that many of the major submarine purchasers (including Pakistan, India, Israel, and China) are in regions of concern and some possess weapons of mass destruction (WMD), which may be deployed on these new submarines, thanks to the relative ease of acquiring cruise missiles on the international market.[2] Finally, still other countries (such as Brazil) may be using new submarine programs to develop a full nuclear fuel cycle, giving them access to highly enriched uranium and possibly encouraging other Non-Proliferation Treaty (NPT) members to do likewise. Thus, there are a number of new submarine-related threats that require further attention by the international community.

To better understand current trends, it is worthwhile to take a closer look at global submarine proliferation by dividing it into its two main categories: 1) diesel submarines (some equipped with new, air-independent propulsion [AIP] systems, discussed below); and 2) nuclear submarines. This issue brief discusses current procurement dynamics and concludes that new national and international controls are needed to limit certain types of submarine proliferation: specifically, to prevent the export of advanced submarines to states that intend to use them for delivering WMD.

Current Submarine Exports

Given statements since September 11, 2001, by many governments opposing the proliferation of WMD and related delivery systems, national perspectives on submarine proliferation can at best be described as "highly subjective." For example, France has made sales of advanced submarines to nuclear-armed countries, even transferring whole production lines and designs, apparently discounting possible threats these exports might cause. Russia continues to be an active exporter of finished diesel submarines and is now providing nuclear reactor and submarine-design technology to China and India. In the Middle East and elsewhere, Germany remains a major submarine exporter, despite the WMD potential of some of its clients. Thus, current major power policies seem to accept the Cold War premise that—in the right hands—new submarines are safe, or at least not an unduly negative influence on regional security. Existing international export regulations on submarine exports (under the U.N. Arms Register and the Wassenaar Arrangement) are remarkably permissive, essentially allowing countries to make their own decisions on exports of diesel and even nuclear-powered submarines, with the only stipulation that they "declare" sales of larger submarines or those equipped with certain types of longer-range missiles. But no actual, international limitations exist.[3]

Diesel and AIP Submarine Proliferation

Sales of diesel and planned AIP submarines and, in some cases, complete production technology, are being undertaken by a number of large producers: Germany's Howaldtswerke Deutsche Werft HDW), France's Direction des Constructions Navales (DCN),[4] Sweden's Kockums, South Korea's Daewoo, and Russia's Rubin Design Bureau.[5]

Among these producers, France is arguably the most active exporter of diesel boats and one that has often provided production technology to sweeten deals with submarine purchasers who want to become producers themselves. Of greatest concern, France has provided Agosta-class diesel boats and production technology to Pakistan, despite a recent terrorist attack that killed a number of French engineers working in the country and Pakistan's refusal to join the NPT. Competition with India is a key motivating factor. India's Defence Ministry announced in 2003 that it had reached a co-production deal for six advanced French Scorpene-class diesel submarines, all of which will be built in India.[6] In addition, France's exports may be creating a secondary market. Pakistan is reportedly offering a French-provided Agosta-class submarine to Saudi Arabia,[7] a country suspected of having its own nuclear ambitions. These transfers will stimulate proliferation tensions in the Persian Gulf, where Iran already has three Russian-provided Kilo-class submarines and might desire eventually to deploy WMD at sea.

Although the United States does not export nuclear submarine technology (except the Trident missile delivery system it shares with Britain) and currently does not produce any diesel boats, it may do so again in the future. In February 2001, President George W. Bush offered to sell eight diesel submarines to Taiwan.[8] In addition, the United States has tacitly approved acquisition by allies of new strategic submarines. Under the past two U.S. administrations, Washington has failed to protest Germany's provision of three Dolphin-class submarines to Israel, which the Israeli Navy has apparently fitted with nuclear-tipped cruise missiles, either of U.S. or Israeli manufacture.[9] Given Israel's location and the ample evidence of terrorist organizations with experience in carrying out suicide bombings and other attacks in Israeli cities, the presence of nuclear weapons on vessels in Israeli harbors is a reason for serious concern. These submarines are especially vulnerable when surfaced and during ingress and egress activities, where preventing unexpected attacks from the sea (including by divers and fast, maneuverable boats) is considerably more difficult than safeguarding nuclear weapons on land. Similar concerns will likely affect new, WMD-armed submarines in South Asia.

Germany has long been a leading producer of advanced diesel submarines and has recently made several troubling sales, including the Israeli deal. As one U.S. naval officer laments of the Type 209 submarines produced by Germany's HDW: "The most popular submarine export of the 1990s, more than 50 Type 209s were sold to 12 countries."[10] Fortunately, to date, few of them (with the exception of the Israeli deal) have been provided to WMD-capable countries or fitted with cruise missiles able to attack land targets. Thus, the major threat is to surface ships and submarines. But this situation may change with the emergence of new clients. Small producers like South Korea have also begun creating a secondary market for German designs, recently offering two Type 1300 submarines—now produced by Daewoo—to Indonesia, a country with growing naval interests.[11] Looking ahead, HDW's new Type 212 submarines will have an AIP capability as well. Any of these submarines could be modified for strategic missions, depending on the delivery systems provided and the WMD capabilities of the recipient state.

German and Swedish technologies, particularly, are leading the way toward the proliferation of more stealthy submarines—reportedly capable of being submerged for nearly one month—using AIP technology. Russia's Rubin Shipyard is also now providing an AIP option on its Kilo-class submarines.[12] These technologies may give states with WMD but without the resources to develop nuclear submarines greater stealth capability and an incentive to put WMD at sea. The technologies are therefore worth investigating in greater detail.

AIP technologies, including liquid-oxygen-using diesel engines and external combustion Stirling engines, allow submerged propulsion without the necessity of using external sources of oxygen. (See Table 1: Current AIP Submarine Technology.)

Some systems employ hydrogen (or methane) fuel cells instead of compressed or liquefied oxygen. However, the volatility of these gases creates the risk of fires and explosions. While vessels operating on AIP technologies generally lack the speed of advanced diesel boats, their ability to remain underwater for much longer periods (operating at approximately four knots) can give them possible advantages in conflicts lasting longer than a few days, in which a normal, diesel-only submarine would have to surface (thus revealing its position). Compared to nuclear submarines, their smaller size gives them access to littoral waters and their cost is approximately one-eighth as much.[14] However, AIP technology is not foolproof. Russia, for example, has had problems perfecting its design. The United States, which deployed a system using a hydrogen peroxide-based oxidizer on its X-1 midget submarine in the late 1950s, discontinued the program after a dangerous explosion.[15] A British program in the 1950s had similar difficulties involving a dozen fatalities.[16]

As noted above, a perhaps more troubling aspect about a number of recent submarine deals is the willingness (even eagerness) of producers to provide cruise missile systems as part of these transfers. Of greatest concern in regards to the WMD delivery threat are cruise missiles that can be fired from torpedo tubes. Such technologies have only been available on the international market for the past decade, although they were developed by the superpowers during the 1970s. While useful for deterrence, these weapons, of course, can also be used offensively. Unfortunately, a number of countries can provide these missiles. Russia, for example, has expressed its willingness to provide 300-km range Klub missiles to India as part of a deal to send two nuclear submarines to the Indian Navy for lease.[17] These missiles are believed to be nuclear-capable and would move India very quickly into the ranks of nuclear-armed navies. Pakistan has recently tested a 300-mile-range cruise missile, although not yet a sea-based variant.[18] China reportedly will also receive Klub missiles for its newest Kilo-class diesel boats on order from Russia.[19] Even states like Egypt, Turkey, and Chile have U.S.-provided Harpoon anti-ship cruise missiles capable of being fired from submarines,[20] which could be used for short-range land-attack missions as well, especially in a crisis.[21]

However, while diesel AIP submarines with cruise missiles do pose serious new concerns to opponents, they are unlikely to provide the invulnerable deterrent capabilities that their possessors seek at least for a decade or more, until they acquire longer-range missiles, proven (and reliable) propulsion technologies, and much greater experience in safe submarine operations. Instead, they are likely to suffer from significant near-term vulnerabilities and risks of serious accidents.

In terms of stealth, these diesel and AIP boats will still need to rise at least to periscope depth for communication during crises and will have to snorkel in order to recharge their batteries when AIP systems exhaust themselves. These requirements are especially problematic given the restricted areas near opponents' shores where they will have to operate in order to keep their short-range missiles at a lethal distance. While AIP boats should increase stealth, many experts doubt the actual (vs. advertised) submerged capabilities of AIP boats. Their effectiveness ultimately depends not only on their engines, but also on the ability of their crews to operate the boats effectively. In many cases, this takes years of training. Early stationing of nuclear weapons on these vessels will only increase the associated risks.

Nuclear Submarine Proliferation

Although a relatively small number of countries currently appear to be interested in acquiring nuclear-powered submarines—given their high costs—trends toward continued steady proliferation and the first sales of nuclear-powered boats are also noticeable. While there are compelling rationales for states to seek comparatively cheaper and safer diesel submarines,[23] particularly in countries whose only goal is to defend their coastal waters, specific regional pressures, matters of national prestige, and arms race dynamics continue to drive a handful of states to seek nuclear submarines, whether through domestic production or imports. This raises the likelihood that additional states might acquire full-fuel-cycle nuclear capabilities, giving them the option of diverting highly enriched uranium (HEU) fuel to a bomb project.

Ironically, part of the reason for the race to the sea among new nuclear powers may be the international demonstration effect. The most advanced navies in the world (U.S., French, and British) now operate only nuclear-powered submarines, sending a potent signal to other states that nuclear power is better. Moreover, the world's nuclear powers have steadily placed a higher and higher percentage of their nuclear weapons onto submarines. These goals were specifically embodied in the text of the U.S.-Russian START I agreement and is the clear direction of U.S. and, to a lesser extent, Russian nuclear forces in complying with the 2002 Moscow Treaty. France and the United Kingdom have also moved all of their nuclear weapons onto submarines. Meanwhile, China is gradually expanding its nuclear navy and becoming more active in using it. Beijing recently sent a nuclear-powered Han-class, cruise-missile submarine (SSN) into Japanese territorial waters, stirring regional tensions.[24] With Russian assistance, China will likely put next-generation, nuclear-powered ballistic missile submarines (SSBNs) and SSNs into the water within the coming decade, armed with much-more-capable weapons than those of the current Xia-class SSBN. Thus, the message is clear: great powers have nuclear submarines and deploy nuclear weapons at sea.

This lesson has not been lost on a number of new nuclear powers, including Israel, Pakistan, and India. Among this group, only Pakistan has sought to slow this trend by urging India to agree to a ban on submarine-launched ballistic missiles.[25] However, there has been no interest on India's part in taking up this offer, as New Delhi believes that it has a naval advantage and a critical partner (Russia) willing and able to help it accomplish its goals. India's new naval doctrine, for example, released in April 2004, calls specifically for a sea-based nuclear deterrent.[26]

Despite its nuclear rapprochement with Argentina and apparent abandonment of past plans to develop nuclear weapons, Brazil remains interested in developing a nuclear submarine, purportedly only for coastal defense. However, Brazil's recent reluctance to grant IAEA officials full access to its nuclear facilities may be related to enrichment technology for this program and may indicate other reasons for completing the fuel cycle.[27] In 2000, Brazilian naval officials spoke openly of their plans for a nuclear submarine,[28] and the Brazilian government allotted a new round of funding toward this long-standing project. In 2004, Brazilian Ambassador to the United States Roberto Abdenur responded to recent charges that his country is blocking IAEA access to certain nuclear facilities with the revealing comment, "Submarines are not subject to the safeguards regimen, that's my view of things."[29] In the past, Brazil has made overtures to France for technical assistance and has reportedly already received help from Russian experts.[30] Development of a full fuel cycle in Brazil for a submarine program, unfortunately, could stimulate other countries to pursue a similar route: either to a nuclear submarine or to a bomb.

The United States and other Permanent Five (P-5) members of the United Nations Security Council (UNSC) have sought to halt the proliferation of weapons-grade nuclear material through such efforts as the UNSC Resolution 1540.[31] However, the P-5 have also tended to suffer from a "do as we say, not as we do" problem in regards to the HEU naval fuel issue. For example, while U.S. submarine construction rates have slowed dramatically, U.S. nuclear submarines continue to run on extremely highly enriched fuel (over 97% U-235 according to unclassified sources[32]). The United Kingdom also uses such highly enriched fuel, and France reportedly uses HEU at an over 80% enrichment level in its SSBNs.[33] The key military advantage is that these submarines do not need to be refueled as often. The disadvantage is that these submarines send an example to other navies that bomb-quality fuel is the best power source for submarine reactors, creating demands for a full fuel cycle in countries considering nuclear submarines. This is a dilemma that P-5 nonproliferation policies have failed to address. Preserving treaty exemptions for new, HEU naval fuel production—such as in the current NPT and in draft versions of the prospective Fissile Material Cutoff Treaty—creates loopholes that can undermine anti-trafficking and anti-HEU nonproliferation efforts.


Current trends suggest that the new dynamics of submarine proliferation threaten to bring out some of the worst characteristics of the Cold War arms race at sea, as well as creating certain new and possible even more dangerous threats. In order to determine the safety of submarine exports, states need to reconsider their assumptions about submarine exports and instead raise a series of linked questions before such sales about their likely implications for regional security and global nonproliferation efforts. First, is the recipient state in a region of concern where new submarines are likely to be destabilizing? Clearly, the stimulation of regional naval arms races should be avoided by the international community. Second, does the recipient state possess WMD and is their deployment on the new submarine likely? An emerging practice in new states with WMD is to imitate the P-5 by deploying WMD at sea for both prestige and perceived military advantage. However, lessons from the Cold War period—involving two distant rivals, nuclear propulsion, and long-range ballistic missiles—may not be applicable to today's regional security environments, which are characterized by low numbers of nuclear weapons (increasing pressures to launch on warning), greater proximity to and threats of detection by hostile vessels, and correspondingly shorter missile delivery times (reducing decision-making options and threatening crisis stability). And, third, is the recipient state also attempting to acquire cruise or ballistic missiles to assist in the delivery of submarine weapons? In many submarine sales, the intent of the recipient to use vessels for offensive purposes is clear from the type of weapons it is purchasing. Torpedoes are not effective, for example, for land-attack missions. The purchase of cruise or ballistic missiles raises the prospect that submarines will be used not only for sea-based targets but also to strike strategic targets on land.

Unfortunately, progress toward halting or limiting transfers of submarines intended for strategic uses will require some country (or group of countries) to step forward and make a persuasive case regarding these new threats. Unlike in the past, there are a growing number of states now seeking to deploy WMD at sea and also engaged in regional rivalries that make use of these weapons more likely. Unfortunately, many of these states face serious learning curves before they will be able to operate these new submarines vessels safely, particularly when potentially volatile technologies (such as AIP) are deployed along with WMD in close-in littoral seas. For these reasons, tracking and controlling international submarine proliferation needs to be a much higher priority than it is today. But the considerable profits to be had from submarine sales continue to limit the willingness of national governments to take on this emerging problem, although, ironically, many of sales and the shipyards themselves are actually subsidized by their governments. Accidents or confrontations involving these vessels—especially associated with on-board WMD—would provide a sobering corrective to both exporters and importers alike, but are certainly events that no one wants to take place. For these reasons, the United States and other countries need to elevate these problems on their security agendas in order to prevent such incidents from occurring and to discourage (rather than encourage) naval arms races by new, WMD-capable states.


[1] David Lague, "We All Live for Another Submarine," Far Eastern Economic Review, August 15, 2002.
[2] Nuclear and biological weapons are likely to be the weapons of choice, given their lethality.
[3] For specific details on existing regulations, see James Clay Moltz, "Serious Gaps Emerging in Export Controls on Submarines," NIS Export Control Observer, No. 28 (June 2005), [4] DCN is a state-controlled concern that manages all French submarine construction and includes activities at several shipyards.
[5] The Dutch producer RDM Submarines and British Vickers Shipbuilding & Engineering, Ltd., are also capable of exporting diesel boats, but have no current orders. Several other, small producers could become active exporters in the future.
[6] "Report: Way Cleared for French Submarine Scorpion to Be Manufactured in India," Navbharat Times (New Delhi, India), October 6, 2003.
[7] Intelligence Online (Paris), October 31, 2003,
[8] The deal has been delayed, however, by Taiwanese concerns about the cost (estimated at $8.6-$11.7 billion) and current U.S. inability to produce diesel submarines, although it could likely buy up-to-date designs. See John Feffer, "Taiwan: No Farewell to Arms, But Sales Slow," Asia Times, May 8, 2004, on the Taiwan Security Research,
[9] See Dominic Coldwell, "Flipper wouldn't approve," Al-Ahram, Issue No. 662, October 30-November 5, 2003,
[10] Allen L. Edmiston, "Why We Need Nonnuclear Submarines," Proceedings (U.S. Naval Institute), Vol. 130, No. 1 (January 2004), p. 54.
[11] See report on the website of Indonesian Embassy to Finland, Monthly News Bulletin, September 2003,
[12] Lyle Goldstein and Lt. Com. Bill Murray, "China's Subs Lead the Way," Proceedings (U.S. Naval Institute), Vol. 129, No. 3 (March 2003), p. 58.
[13] Compiled by author from Edward C. Whitman, "Air-Independent Propulsion: AIP Technology Creates a New Undersea Threat," Undersea Warfare, Vol. 4, No. 1 (Fall 2001),, and Richard Scott, "Boosting the staying power of the non-nuclear submarine: Air-independent propulsion system options are maturing," Jane's International Defense Review, No. 11 (November 1999), pp. 41-50.
[14] AIP boats, however, are far slower than nuclear submarines and have to refuel regularly.
[15] Norman Friedman, U.S. Submarines since 1945 (Annapolis, MD: U.S. Naval Institute, 1994), p. 111.
[16] See David Miller, The Illustrated Directory of Submarines of the World (London: Salamander Press, 2002), pp. 326-27.
[17] "Icing on Gorshkov cake for India: N-submarine,", December 3, 2002,
[18] Associated Press, "Pakistan Test-Fires Cruise Missile," August 11, 2005.
[19] Goldstein and Murray, "Undersea Dragons: China's Maturing Submarine Force," p. 166.
[20] David Wood, "Threats emerge from below: thought to be a thing of the past, enemy submarines could be an obstacle to U.S. military might," Navy Times, September 27, 2004.
[21] On converting standard anti-ship cruise missiles to land-attack missions, see Dennis M. Gormley, "Dealing with the Cruise Missile Threat, Adelphi Paper 339," International Institute for Strategic Studies, London, June 2001, pp. 29-33.
[22] Michael D. Wallace and Charles A. Meconis, "Submarine Proliferation and Regional Conflict," Journal of Peace Research, Vol. 32, No. 1 (1995).
[23] Chunyan Ma and Frank von Hippel, "Ending the Production of Highly Enriched Uranium for Naval Reactors," The Nonproliferation Review, Vol. 8, No. 1 (Spring 2001).
[24] Martin Fackler, "Japanese Pursuit of Chinese Sub Raises Tensions," The Wall Street Journal, November 15, 2004, p. A20.
[25] Comments by Pakistani Ambassador to the United States Maleeha Lodhi in presentation on "Pakistan-United States Relations: The Regional and International Security Dimensions," at the Center for Nonproliferation Studies, Monterey Institute of International Studies, Monterey, California, March 1, 2001.
[26] "Think Tank Urges India to Develop Submarine-Based Nuclear Deterrence Capability," New Delhi Institute of Peace and Conflict Studies, August 23, 2004; FBIS document SAP20040826000112.
[27] Larry Rohter, "Brazil Resists Plan to Allow Spot Inspection of Nuclear Site," The New York Times, December 28, 2003, p. 4.
[28] Mark Hibbs, "Brazil May Enrich to HEU for Submarine Reactor Fuel," Nuclear Fuel, 24 July 2000, 7.
[29] Quoted in Larry Rohter, "Nuclear Secrets: If Brazil Wants to Scare the World, It's Succeeding," The New York Times, October 31, 2004, "Week in Review," p. 3.
[30] Yuriy Golotyuk, "Brothers in Arms," Vremya Novostey (Moscow), 9 April 2002; FBIS document CEP20020409000331.
[31] For the full text of U.N. Resolution 1540,
[32] Ma and von Hippel, "Ending the Production of Highly Enriched Uranium for Naval Reactors," p. 91. Recent reports indicate that use of uranium from former U.S. nuclear weapons will require a slight decrease in the enrichment levels to 93% in future reactor cores, although a boost in energy output is also expected. The shift is being made for technical reasons, not nonproliferation considerations.
[33] Ibid. Russian nuclear submarines generally use 21 to 45% enriched HEU. Recent reports indicate that use of uranium from former weapons.

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