The NTI Submarine Proliferation Resource Collection details the submarine capabilities and import/export behavior of several representative countries around the world. The collection focuses on technological improvements to global submarine fleets, such as the spread of nuclear propulsion and Air Independent Propulsion (AIP) technologies, which increase the capability of submarines to deliver weapons of mass destruction (WMD). Additionally, the database tracks conventional submarine proliferation in potential global flashpoints, particularly the Middle East, South Asia, and Southeast Asia.
Submarine proliferation impacts both regional stability and the ability of states to deliver WMD. Since the end of the Cold War, the total number of active submarines in the world has fallen, largely as a result of large-scale decommissioning of former Soviet vessels.  However, the number of countries operating submarines has increased, due largely to ongoing regional tensions in the Middle East, South Asia, and East Asia. Countries who seek to acquire submarines can rely on a competitive global export market, which is only lightly regulated by international export controls.
An Evolving Export Market
Although the number of states acquiring submarines has grown in recent decades, the group of countries exporting submarines has remained relatively small. Today, France, Germany and Russia are the three most active exporters of conventional submarines. France's Direction des Constructions Navales Services (DCNS) and Germany's Howaldtswerke Deutsche Werft (HDW) are the two principal submarine producers in their respective countries.  Between them, they have exported to approximately 21 navies.  Meanwhile, Russia has a number of design and construction enterprises, and has exported conventional boats to some 14 navies around the world. Notable recipients of Russian diesel-powered submarines include China, Iran, India, and Vietnam. As Japan has eased its ban on military exports, Tokyo has emerged as a challenger to the existing submarine market’s status quo.  South Korea has also entered the submarine export market, delivering its first Daewoo-built attack submarines to the Indonesian Navy in 2016. 
Competition among exporters for lucrative construction contracts can be fierce, and this has often led to producers offering technology transfer to secure deals. One example is France's production technology transfer to Brazil as part of its 2008 sale of Scorpène-class vessels.  Technology transfers of this kind will result in the proliferation of submarine producers as recipients become capable of constructing their own submarines.
Air Independent Propulsion (AIP) technology provides diesel-powered submarines with greater submerged endurance (several weeks as opposed to several days), thereby enhancing survivability.  This is achieved through the use of liquid or compressed oxygen or hydrogen fuel cells that allow vessels to stay submerged for longer periods without the need for external sources of oxygen.  AIP vessels are smaller than nuclear powered submarines, giving them greater access to shallow, littoral waters. For nations that are unable or unwilling to develop nuclear powered submarines, AIP offers an attractive alternative that improvs submarine performance without the cost of nuclear propulsion.
Implications for Regional Stability
New capabilities for conventionally-powered submarines, such as AIP technology and cruise missile delivery systems, have heightened concern that nuclear armed states outside the Treaty on the Non-Proliferation of Nuclear Weapons (NPT), such as Israel, India, and Pakistan, could mount nuclear warheads on submarine launched delivery systems.  These states, taking the example of the NPT-recognized nuclear weapon states, hope to ensure the survival of their nuclear deterrent in the event of attack. Although such sea-based deployments may increase stability by ensuring a second-strike capability, they also have the potential to trigger arms races that create greater instability. Additionally, some experts are concerned that mounting nuclear weapons on submarines increases their vulnerability to terrorist attack, and that states may lack sufficient command—and—control to reliably manage a submarine—based nuclear force.  The proliferation of conventional submarines, even among states that do not possess a nuclear weapons capability, may also precipitate regional arms races.
Despite the advent of AIP technology, a number of states continue to pursue nuclear propulsion, often for reasons of national prestige or arms race dynamics. India and Brazil have taken significant steps toward this goal. Although India began work on its so-called Advanced Technology Vessel (ATV) in the 1970s, the project ran into a number of financial and technical difficulties.  In July 2009, however, India launched its first ATV submarine, the INS Arihant, at the Ship Building Centre in Vishakapatnam, and commissioned it into the navy.   New Delhi plans to build a fleet of three ballistic missile submarines (SSBNs) that will perform a strategic nuclear role, with each vessel likely to carry 12 Sagarika submarine launched ballistic missiles (SLBM).  By comparison, Brazil's development of a nuclear-powered submarine is far behind India's, and has a target launch date of 2025.  Between 1980 and 2005 Brazil invested heavily in the development of uranium enrichment, fuel fabrication and reactor technology, and is now in the final development stages of its Pressurized Water Reactor, the RENAP-11.  
In their bids to develop nuclear propulsion, both India and Brazil have received assistance from other states. Russia has been India's key partner. In addition to Russia's export of nuclear reactor technology to India, the Soviet Union leased a Project 670 nuclear-powered cruise missile submarine to New Delhi in 1988.  The vessel's reactor was operated by Russian crew, and the submarine was returned to the Soviet Union in 1991. Due to delays in its indigenous program, India signed an agreement with Russia in 2004 to lease another nuclear-powered attack submarine, a Project 971 Shchuka-B (NATO designation Akula II), inducted into the Indian Navy as the INS Chakra in April 2012. 
Meanwhile, France is assisting Brazil in constructing the hull for its first nuclear vessel. Brasilia originally approached both Russia and France as possible suppliers, but eventually signed a contract with France in September 2009. The contract states that France will supply Brazil with the hull for a nuclear vessel on the condition that Brazil will be solely responsible for the vessel's nuclear components.  Any spread of naval nuclear technology beyond these two states creates nonproliferation concerns due to a loophole in the Treaty on the Non-Proliferation of Nuclear Weapons (NPT). This loophole allows states to withdraw fissile material from international safeguards if it is to be used for military reactor fuel, thus creating the possibility that fissile material will be diverted to a nuclear weapons program. 
When considering the export of submarines, states often prioritize financial gain over security concerns because of the lucrative nature of construction contracts. Russia's provision of nuclear reactor and submarine-design technology to China and India are clear examples.  Additionally, multilateral export control regimes contain few restrictions on the sale of submarines, partly because they have historically been used for defensive purposes. The UN Arms Register requires states to declare the transfer of warships that displace 500 metric tons, or are able to fire missiles or torpedoes with a range of 25 kilometers or more.  The Wassenaar Arrangement goes further by requiring states to report the sale of vessels that displace 150 tons, as well as those that are equipped to fire missiles or torpedoes with a range of 25 kilometers.  However, declarations to the United Nations have not been comprehensive, and neither of these regimes bans the sale of any type of submarine.  The NPT also allows the export of nuclear submarines, as nuclear propulsion is viewed as an acceptable use of nuclear energy. As a result, there is little to prevent states from selling submarines to countries located in regions of high political and military tension.
 James Clay Moltz, "Global Submarine Proliferation: Emerging Trends and Problems," Nuclear Threat Initiative Issue Brief, March 2006, www.nti.org.
 "Agosta SSK," DCNS, www.dcnsgroup.com; "Israel buys two nuclear-capable submarines," The Washington Post, August 25, 2006, www.washingtonpost.com.
 "Submarines," Howaldtswerke-Deutsche Werft, www.hdw.de; Pierre Tran, "DCNS Pins Hopes on Exports," Defense News, November 8, 2010, www.defensenews.com.
 Kyle Mizokami, "Japan's Emergence Defense Industry," U.S. Naval Institute, February 25, 2015, www.usni.org.
 Franz-Stefan Gady, "South Korea Launches 2nd Indonesian Attack Submarine," The Diplomat, October 24, 2016, http://thediplomat.com.
 "Brazil and France in Deal for SSKs, SSN," Defense Industry Daily, December 12, 2014, www.defenseindustrydaily.com.
 Milan Vego, "The Right Submarine for Lurking in the Littorals," U.S. Naval Institute, Proceedings Magazine, June 2010, Vol. 136, p. 6.
 "Sub Proliferation Sends Navies Diving for Cover," Jane's International Defence Review, August 1, 1997.
 James Clay Moltz, "Serious Gaps Emerging in Export Controls on Submarines," NIS Export Control Observer, produced by the James Martin Center for Nonproliferation Studies, June 2005, p. 23.
 Panda and Vipin Narang, "Pakistan Tests New Sub-Launched Nuclear-Capable Cruise Missile. What Now?" The Diplomat, January 10, 2017, http://thediplomat.com.
 T.S. Gopi Rethinaraj, "ATV: All at Sea Before It Hits the Water," Jane's Intelligence Review, June 1, 1998.
 "Submarine Forces, India," Jane's Underwater Warfare Systems, August 14, 2009, www.janes.com.
 Amit Saksena, "Can India Accommodate the INS Arihant?" The Diplomat, January 26, 2015, thediplomat.com.
 Rajat Pandit, "Strategic Karwar Naval Base Set for Major Expansion," The Times of India, May 20, 2012, articles.timesofindia.indiatimes.com; Peter Crail and Eben Lindsey, "India Launches First Nuclear Submarine," Arms Control Today, September 2009, www.armscontrol.org.
 "Brazil to Join Elite Club of Nations Building Nuclear-Powered Submarines," Agence France-Presse, June 5, 2014, www.scmp.com.
 "Project 670 Skat," Federation of American Scientists, www.fas.org.
 "Brazil Accelerates Reactor Work for Nuclear Submarine Program," Sea Power, Vol. 47, No. 7 (July 2004), p. 44; in ProQuest Information and Learning Company, http://proquest.umi.com; "Programa de “Submarinos e Submarinos Nucleares de Ataque(SNA) da Marinha do Brasil," www.infomarmb.hpg.ig.com.br.
 "India to get Russian nuclear submarine for 10-year lease," RIA Novosti, March 17, 2010, www.rian.ru.
 "India Inducts Russian Made Nuclear Submarine into Navy," The Times of India, April 4, 2012, http://articles.timesofindia.indiatimes.com; Sarah Diehl and Eduardo Fujii, "Brazil's Pursuit of a Nuclear Submarine Raises Proliferation Concerns," WMD Insights, March 2008, www.wmdinsights.com.
 "Brazilian Submarines: DCNS Passes Major Milestone Towards One of Group's Biggest Contracts Ever," September 7, 2009, www.dcnsgroup.com; "Acordo Entre o Governo da República Federativa do Brasil e o Governo da República Francesa na Area de Submarinos" [Agreement Between the Government of the Federative Republic of Brazil and the Government of France in the Area of Submarines], Brazilian Defense Ministry, December 23, 2008, www.defesanet.com.br.
 Chunyan Ma and Frank von Hippel, "Ending the Production of Highly Enriched Uranium for Naval Reactors, Nonproliferation Review, Spring 2001, p. 87.
 James C. Bussert, "China Copies Russian Ship Technology for Use and Profit," Signal Online, June 2008, www.afcea.org.
 "Considerations for Reducing the Benchmark Range for Torpedoes on Warships of Less Than 500 Metric Tons," 2009 Group of Governmental Experts on the UN Register of Conventional Arms, United Nations Office of Disarmament Affairs, www.un.org.
 "Wassenaar Arrangement on Export Controls for Conventional Arms and Dual-Use Goods and Technologies," July 2004, www.wasenaar.org.
 James Clay Moltz, "Serious Gaps Emerging in Export Controls on Submarines," NIS Export Control Observer, produced by the James Martin Center for Nonproliferation Studies, June 2005, p. 24.
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The submarine proliferation resource collection is designed to highlight global trends in the sale and acquisition of diesel- and nuclear-powered submarines. It is structured on a country-by-country basis, with each country profile consisting of information on capabilities, imports and exports.
This material is produced independently for NTI by the James Martin Center for Nonproliferation Studies at the Middlebury Institute of International Studies at Monterey and does not necessarily reflect the opinions of and has not been independently verified by NTI or its directors, officers, employees, or agents. Copyright 2017.