How Japan, South Korea are building up naval capabilities for China threat

SINGAPORE — As China dwarfs other Pacific nations with its naval expansion in terms of raw tonnage, number of hulls and the amount of capabilities hitting the sea, US allies Japan and South Korea are scrambling to modernize their own naval capabilities.

The scale of China’s naval expansion is stark. According to the BBC, citing a CSIS report, China’s four major shipyards produced 39 warships with a total displacement of 550,000 tonnes between 2019 and 2023. That same BBC piece also added that as of 2024 the People’s Liberation Army Navy (PLAN) had 332 warships to the US Navy’s 319.

Adding to the pressure for more naval capabilities is the dependence of East Asia’s economies on seaborne trade, meaning nations need a bolstered navy to protect incoming shipments.

In addition to China’s growing threat, both US allies also have to also contend with nuclear-armed North Korea’s missile programs as well as its own naval ambitions that has seen the Stalinist regime pursue its own nuclear-powered submarine.

So, in the race to modernize, what are Japan and South Korea doing?

Japan Increases Ballistic Missile Defense

Japan has stepped up defense spending over the past decade as both China’s and North Korea’s capabilities advance, with the country having allocated record defense budgets every year over the past decade, based on its budget documents.

The most significant naval shipbuilding program in Japan is for a pair of Aegis System Equipped Vessels (ASEV) sea-based Ballistic Missile Defense (BMD) platforms for the Japan Maritime Self-Defense Force (JMSDF) and will be used together with its other Aegis-equipped destroyers for protecting Japan’s airspace, according to Japan’s Ministry of Defense (MoD).

Japan had embarked on the ASEV program in 2020 following the cancellation of an attempt to introduce the Aegis Ashore system.

The ships will each displace approximately 14,000 tons and will be equipped with the Lockheed-Martin SPY-7(V)1 multi-function radar as its primary sensor for 128 Mk.41 Vertical Launch System (VLS) cells for SM-2, SM-3, SM-6 air-and-missile defense interceptors or Type 12 anti-ship missiles as well as Tomahawk cruise missiles, according to Naval News.

Construction of both ships is underway with the first ship being built by Mitsubishi Heavy Industries and the second by Japan Marine United. The ASEVs are due to be commissioned in early 2028 and 2029, the MoD said.

Japan has also been steadily introducing new submarines into the JMSDF to replace the older Oyashio-class, commissioning one Taigei-class boat per year since 2022.

Japan’s other major naval program is the conversion of two Izumo-class Helicopter-Destroyers into aircraft carriers for the Lockheed-Martin F-35B Short Take off and Vertical Landing (STOVL) variant of the Lightning II stealth fighter.

Izumo and sister ship Kaga will receive a squared off flight deck along with other modifications to operate the F-35B, including the addition of a coating at the rear of its flight deck to enable it to withstand the heat from the STOVL jet’s exhaust gases during landing operations.

Conversion of the Izumo began in 2020 and is expected to be completed later this year or early 2027, while Kaga is expected to be completed in Japan’s fiscal 2027, beginning April 1.

In addition to these major programs, Japan is also continuing its build of the Mogami-class frigate for the JMSDF, with the introduction of the Improved Mogami design that has also been chosen by Australia and is in the running for New Zealand’s frigate program, with the latter’s defense minister announcing the competition in May.

Japan is also introducing the Sakura-class Offshore Patrol Vessels into service from March 2027 and its recent defense budget request included seeking funding for unmanned transport vessels for moving troops and equipment from mainland Japan and the main island of Okinawa to its small outlying islands in the East China Sea, per the budget request.

South Korea’s Plans To Join Nuclear Sub Club

Like Japan, South Korea has a robust shipbuilding industry that has been vital to transforming it into a regional naval power alongside a defense industry that has gone from strength to strength, enabling it to indigenize an increasing portion of its armed forces.

The country recently saw the fulfillment of a long-time wish when US President Donald Trump agreed in May to allow South Korea to develop its own nuclear powered submarines.

South Korea’s defense establishment sees the introduction of nuclear-powered attack submarines as having taken on an increased importance as its northern neighbor steps up the development of its own nuclear submarine program to carry its submarine-launched ballistic missiles.

The South Korean nuclear-powered attack submarines will also have greater endurance than their diesel-electric counterparts, enabling them to stay out at sea for longer periods of time and allow them not just to stalk North Korean ballistic missile submarines but also allow them to rapidly respond to any land-based North Korean missile launches, according to research fellow at the Korea Institute of Defense Analyses Yu Ji-hoon during an interview on South Korea’s Arirang News.

The US ally is also pursuing a new class of 7,000-ton class destroyers that it is seeking to be equipped primarily with indigenous systems such as its own integrated sensor suite, combat management system, VLS and missiles, although the ships will still be powered by the GE Aerospace LM2500+G4 marine gas turbine engine.

Hanwha Ocean will be responsible for the design and construction of the first KDDX, which is expected to enter service in 2032. The company has also been tapped to supply a frigate to Thailand, with the Southeast Asian country announcing on Monday that the Korean shipbuilder has won a competition against rival South Korean shipbuilder Hyundai and Singaporean, Turkish shipyards for the contract, with the Thai government set to announce further details later in September.