Japan is bolstering its maritime capabilities with Uncrewed Surface Vessels (USV) in response to China’s aggressive actions in the East China Sea, marking a strategic shift in defense technology and the US-Japan alliance.
This month, the Indo-Pacific Defense Forum (IPDF) reported that the Japan Maritime Self-Defense Force (JMSDF) is advancing its maritime capabilities by prioritizing the implementation of USVs, seen as a significant enhancement in intelligence, surveillance and combat support.
IPDF says this strategic move comes in response to China’s repeated incursions around the Japanese-administered Senkaku Islands in the East China Sea. For instance, the source notes that in a notable incident in June 2024, Chinese vessels entered Japanese waters for a record 64 hours.
Stephen Nagy, an international relations professor at Japan’s International Christian University, emphasized to IPDF the importance of enhancing maritime domain awareness capabilities in the Sea of Japan, across the Taiwan Strait, and in the South China Sea.
He highlighted the need for mine countermeasures and antisubmarine warfare to counter potential blockades by China’s People’s Liberation Army-Navy (PLA-N).
IPDF says Japan’s 2024 defense white paper highlights the importance of USVs in enhancing national defense. It notes that these vessels can operate autonomously and are safer and more cost-effective than crewed vessels. It also emphasizes that USV collaboration with the US Navy is crucial for technological innovation.
IPDF notes that Japan’s partnership with JMU Defense Systems has delivered a USV for testing on the JMSDF’s latest Mogami-class frigate. The report says the frigate is intended to serve as the mother ship for uncrewed underwater and mine disposal vessels.
Furthermore, IPDF mentions that Japan is allocating over US$160 million for research and development in 2024 to transition to combat-support USVs capable of threat detection and intelligence-gathering with advanced submarine navigation technology.
USVs can help Japan even up its military balance with China, which has gradually become lopsided in favor of the latter regarding quantity and perhaps also quality.
In a July 2024 Japan News article, Kojiro Tanikawa pointed out that while China has been increasing the number of its warships and enhancing their capabilities in recent decades, with 88 modern frigates and destroyers in 2023, the number of JMSDF combat ships has stayed around 50.
Such a numbers gap may put Japan at a disadvantage. Sam Tangredi points out in a January 2023 Proceedings article that in naval warfare, the adage “quantity has a quality all its own” rings true, as historical analysis reveals that in 25 out of 28 naval wars the side with the larger fleet won.
Tangredi points out that even when opposing fleets have similar technology, the larger fleet usually wins as technological advantages are temporary and quickly countered by adversaries.
He underscores that in conflicts between near-peer naval forces, a substantial fleet size coupled with the ability to replenish losses often outweighs technological superiority.
Questioning whether superior strategy, technology or training can make up for a numerical disadvantage, Tangredi points to historical examples that emphasize the critical role of mass in naval strategy.
He challenges the belief that smaller, technologically advanced fleets can triumph over larger ones, highlighting history’s tendency to favor the side with numerical superiority in naval warfare.
In line with that, Toshi Yoshihara mentions in a June 2020 CIMSEC article that by 2030 the PLA-N could have more than 450 ships while the JMSDF won’t be much larger than it is at the time of his writing.
Yoshihara says Japan maintains a comfortable 45% lead over China in tonnage per combatant. Still, he says that advantage might be short-lived as China puts more carriers, cruisers and destroyers in service.
For firepower, Yoshihara points out that in 2020 China had 75% more vertical launch systems (VLS) than Japan and that China’s anti-ship cruise missiles considerably outrange those of Japan.
While USVs can serve as a stopgap measure to address the numbers and firepower gap, Tanikawa says that Japan has been slow to adopt USVs despite the proven effectiveness of Ukrainian USVs in the Black Sea versus Russian targets. He also says Japan does not have USVs for attack purposes.
While Japan can deploy USVs as a force multiplier to offset its numbers disadvantage versus China, they can do more than enhance maritime domain awareness, mine countermeasures and antisubmarine warfare.
In a March 2023 CIMSEC article, Kyle Cregg discusses the “Every Ship a Surface Action Group (SAG)” concept, a distributed future force architecture in which every manned ship can operate far from each other, surrounded by multiple VLS-equipped and optionally manned Large Unmanned Surface Vessels (LUSV).
He believes combining manned and unmanned teams will create more powerful SAGs than a single manned ship or manned SAG functioning independently, allowing for the quick up-gunning of traditional naval platforms and amphibious assault ships.
Cregg says the “Every Ship a SAG” concept will reduce maintenance and repair requirements and the risks involved in operating in dangerous and contested waters. He adds that the concept bridges today’s nascent USV capability and a more USV-forward autonomous future.
However, Cregg acknowledges challenges in implementing the “Every Ship a SAG” concept, such as project budget and management issues, munitions manufacturing shortfalls and integrating various lines of effort to field increasingly capable and autonomous LUSVs.
Japan’s USV program could be a focal point for enhancing already close US-Japan naval cooperation. In September 2023, the JS Kumano frigate, the USS Oakland, USV Ranger and USV Mariner conducted a bilateral naval exercise in Sagami Bay. The exercise was hailed as an opportunity for the US and Japan to strengthen USV research and development efforts.
Furthermore, Vincent Wroble mentions in a June 2021 Proceedings article that as the US grapples with a shrinking naval shipbuilding base, it should allow the construction of USVs in allied shipyards such as those in Japan and South Korea.
Wroble discusses the pros and cons of that approach, saying that allowing foreign construction of USVs reduces costs and leverages Japan and South Korea’s advanced shipbuilding capabilities.
However, he says that securing basing rights for USVs would be paramount, as maintenance cannot be done at sea, and that the idea of building USVs in allied countries may face stiff resistance from large US shipbuilders and conservatives in the US government.