Growing number of submarines shows arms race below the waves

The threat and the promise of submarines played out on opposite sides of the world this year.

In early March, a U.S. Navy submarine sank the Iranian corvette IRIS Dena off Sri Lanka with a MK 48 torpedo. About 87 of the crew were killed.

Near the end of May, a South Korean submarine arrived at Canadian Forces Base Esquimalt, in British Columbia, after an 8,400-mile trip across the Pacific. Korea is hoping to convince Canada to buy its submarines — business also sought by Germany.

The sinking and sales pitch were reminders of the tactical potency of submarines and the status of having an undersea force.

More than 480 submarines from more than 40 nations currently operate in the oceans of the world, according to a 2025 count by the international data aggregator World Population Review. The submarine forces range from the all-nuclear-powered U.S. fleet of about 67 fast-attack, ballistic-missile and guided-missile submarines to the one-sub force of Poland.

Although the U.S. exported a significant number of subs early in the Cold War, it hasn’t built a conventionally powered (diesel-electric) sub since the USS Blueback was commissioned in 1959. That’s left the sub market to the rest of the world.

Navy Chief of Operations Adm. Daryl Caudle said on March 30 at a Center for Strategic and International Studies event that the U.S. is committed to an all-nuclear fleet.

“We made a decision that the only true sub is one with nuclear power,” Caudle said. “It’s just not something we are going to turn back on.”

Caudle said the Navy could, perhaps, procure large conventionally powered unmanned undersea drones.

“But as far as going to a full-scale manned diesel submarine? — It isn’t happening,” he said.

Mark Cancian, a Marine veteran who is an analyst at CSIS, says the U.S. couldn’t build submarines for export even if it wanted.

“The United States is unable to accelerate its own submarine production until the mid-2030s because of constraints in shipyards and the labor force,” he said.

While the Cold War spurred submarine building after World War II, regional conflicts now drive much of the market: China and Taiwan; India and Pakistan; North Korea and South Korea; Iran and Israel.

“Submarine proliferation impacts both regional stability and the ability of states to deliver (weapons of mass destruction),” Nuclear Threat Institute says on its website. “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.”

The Soviet Union heavily exported its diesel-electric submarines, selling or giving allies 60 “Whiskey-class” submarines in the two decades before 1980. The submarines went to China, North Korea, Cuba, Egypt, Poland, Syria, Bulgaria and Albania, according to NTI. The modern Kilo-class went to China, India, Indonesia, Vietnam and Venezuela.

Russia has largely resisted transferring nuclear sub technology to other nations, with the exception of China. In 2012, for the first time, it leased an Akula-class nuclear submarine to India.

China is the third major power in the submarine sales or transfer mix. It has followed dual tracks, rapidly building conventionally powered submarines to scale up its Navy, while adding more nuclear boats to modernize the mix.

The Pentagon, in its annual analysis of Chinese military power, reported in December that China’s People’s Liberation Army Navy has 60 submarines, with six attack submarines and six missile submarines powered by nuclear reactors. Taiwan has two conventional-powered submarines.

Bryan Clark, a former Navy submariner who is now a senior fellow at the Hudson Institute, said the best Chinese submarines use air-propulsion technology that reduces cavitation — a sound a traditional screw propeller creates when submerged.

“Chinese submarine sales could be a worrisome sign because the Type 039A Yuan-class submarine is very quiet and can employ supersonic anti-ship missiles,” Clark said. “It could give a smaller country a very capable way of threatening sea lanes or neighbors at ranges and speeds that drones cannot reach.”

Much of the submarine activity is focused on the 1.4 million square-mile South China Sea. Unlike the globe-straddling zones of competition between the U.S. and Soviet Union, the focus today is on China’s anti-access/area denial (known as “A2/AD”) through the Taiwan Strait and South China Sea.

“PLA Navy submarines are central to China’s strategy to deny adversary forces access to waters within the First Island Chain,” the 2025 Pentagon report said.

About $3 trillion in annual trade moves through the South China Sea each year, according to a Pentagon estimate.

The United States says it wants to balance the nuclear-powered submarine presence in the region through its AUKUS program, which will allow Australia to eventually buy some of the Navy’s older Virginia-class nuclear attack submarines and develop their nuclear-powered technology.

The biggest military in the area is Japan. It operates about 23 submarines of a domestic design, though it has purchased a Swedish air-propulsion system to use on its Sōryū-class submarines. As a close ally, the United States has sold UGM-84L Harpoon Block II submarine-launched missiles to Japan.

South Korea has 22 submarines and enough shipyard capacity for an aggressive overseas sales effort on its KSS-III attack submarine its seeking to sell Canada and other countries. It has sold submarines to Indonesia and as the trip to British Columbia showed, is eager to add Canada to its customer list.

The domestically-designed Dosan Ahn Changho class, which NTI said “represents South Korea’s emergence as a highly capable manufacturer of diesel-electric submarines.”

Seoul plans to launch its first nuclear-powered Jang-Bogo-N sub in the mid-2030s, with a timetable to have the boat in service by the later part of the next decade. In May, the Ministry of National Defense announced a plan calling for four 8,000-ton fast attack boats, about the size of the U.S. Virginia-class submarine.

North Korea has about 24 submarines, mostly variations of Russian or Chinese designs, and in December 2025 the country unveiled in-progress construction of what the military says is its first new nuclear-powered missile submarine. The nuclear-powered capability has not been independently verified.

Japanese Defense Minister Shinjiro Koizumi said in November 2025 that the country was reconsidering its longtime self-imposed ban on nuclear-powered vessels.

“The environment surrounding Japan is truly becoming so severe that we must debate whether to continue with diesel as we have, or to opt for nuclear-powered submarines,” Koizumi said.

The United States, Russia and China account for more than 40% of submarines, and some of the largest second-tier fleets are in the Indo-Pacific region, but subs are built, bought and sold around the world.

India and Pakistan continue to develop nuclear-powered vessels in a region with ongoing tensions. India commissioned INS Arighaat in August 2024 — a 6,000 ton submarine with a light water reactor that has test-launched a submarine launched ballistic missile from the Bay of Bengal.

In Europe, the United Kingdom and France operate nuclear-powered submarines in their navies. Germany does not, but exports its conventionally powered designs to countries such as Argentina, Brazil, Chile, Colombia, Greece, India, Indonesia, Israel, Singapore, South Korea, Norway and Turkey, according to NTI

In 2021, Norway and Germany signed a pact to produce six Type 212CD submarines — two for Germany and four for Norway. The first boat in the 5 billion EURO deal is scheduled for delivery to Norway in 2029.

France’s Naval Group exports Scorpène-class diesel-electric submarine and conventionally powered versions of the French nuclear-powered Barracuda-class. Customers have included Brazil, Malaysia, India, Chile, Indonesia and the Netherlands.

The Todaro-class submarines built by the German-Italian Submarine Programme plans to sell boats to Qatar. Italy had a joint submarine project with Russia that it terminated in 2014 with the invasion of the Crimea by Moscow.

Sweden has exported three classes of submarines to Singapore, Australia and Denmark, and retrofitted Japanese subs with its air-propulsion system.

As navies seek to modernize for advantages against regional adversaries, the demand for submarines is likely to continue to rise, experts say.

“Not many countries can afford an aircraft carrier, but they can afford a submarine,” said Cancian, the CSIS analyst.