Sub Hunter: The Hyuga, a Japan Maritime Self Defense Force helicopter destroyer, can carry up to 11 aircraft for its anti-submarine warfare mission. (US Navy)
TOKYO — Although the Japanese military does not have a stated strategy for countering Chinese anti-access/area-denial (A2/AD) threats, analysts say its decades-long buildup of anti-submarine warfare (ASW) capabilities means it is increasingly able to play such a role.
Formally, the mission of the Japan’s Navy remains protection of sea lines of communication and defense of the homeland in the event of direct invasion.
But the current mid-term defense plan and the creation of a more “dynamic defense” strategy to counter China has seen the focus shift from the north-western Pacific to supporting US Navy carrier strike groups in the seas surrounding Japan. Invasion forces at sea are now presumed to come from China, not Russia.
Japan’s 30-year history of bolstering the ASW mission, particularly the addition of increasingly large “helicopter carriers,” new Aegis destroyers and ISR capabilities, means the Navy in particular and the Self-Defense Forces in general are quietly building the ability to counter China’s A2/AD strategy, according to analysts.
The Navy has also been introducing P-1 maritime patrol aircraft, upgraded SH-60K sub-hunting helicopters and next-generation 3,300-ton Soryu-class submarines — the first Japanese submarines to be equipped with air-independent propulsion systems. The Navy operates five of the attack subs and 11 older Oyashio-class vessels. It plans a total fleet of 22 submarines.
“Chinese A2/AD abilities that have attracted attention are China’s increasing submarine fleet, the DF-21D [anti-ship ballistic missile], anti-ship cruise missiles, as well as China’s new Type 052D destroyers with enhanced air defense capabilities,” said Corey Wallace, a Japan defense expert at the University of Auckland in New Zealand.
“To deal with the subs, Japan already has a lot of what it needs in place. Japan’s past emphasis on ASW and other capabilities for assuring the integrity of its maritime perimeter gives it a base from which it could easily recalibrate its [Navy] to help clear the way for the [US Navy] to insert itself into any conflict relating to Taiwan or Okinawa,” he said.
Recent developments support the idea that Japan is developing, if only indirectly, a counter-A2/AD strategy.
In August, Japan unveiled the first of two planned 27,000-ton helicopter destroyers. The Izumo-class ship — the largest Japanese warhip since World War II — can carry 15 helicopters. In 2009 and 2011, the Navy also commissioned two new third-generation 20,000 ton, Hyuga-class helicopter destroyers, each capable of deploying 11 helicopters. The primary mission of both classes is ASW, but they are also anti-aircraft warfare capable and can conduct multipurpose command-and-control functions.
“If China’s A2/AD strategy is composed of quiet diesel subs, land-based cruise missiles, ship-based anti-ship cruise/ballistic missiles and land-based aircraft, as well as [electronic-warfare]/cyber capabilities, a Japanese counter-A2/AD strategy would be designed to counter these,” said James Manicom, a research fellow at the Centre for International Governance Innovation. “Well, we know that Japan has been bolstering its ASW capability, most recently with the Izumo but also with the Hyuga and other ships of that nature. These can do dual-use humanitarian assistance and disaster relief, and ASW, and these predate the last [mid-term defense plan].”
The Navy also intends to replace its remaining two Hatakaze-class guided-missile destroyers with the latest Atago-class ship, a version of the US Arleigh Burke-class destroyer. The Aegis-equipped ships are capable of anti-aircraft and anti-surface warfare.
“There are two points about the buildup,” said Alessio Patalano, a Japan naval expert at Kings College, London. “One is strategic. Japan has always had a denial strategy and the main theater of focus has moved from Russia to China. The second is technological. Japan is buying into lots of hardware that can be used for fleet air and missile defense. The new Aegis ships have highly advanced capabilities that are essential for these missions,”
Other developments, including increasing deployment of an Air Self-Defense Force squadron to Okinawa, increased ISR capabilities, discussion of the purchase of UAVs, the building of a forward-based monitoring station on Yonaguni Island barely 70 miles from Taiwan, are not only connected to defending Japan’s maritime periphery, denying sea control to the Chinese PLAN and defending Japan’s sea lines of communication. They also “are implicitly connected to Taiwan’s security as well, which requires US access and as much freedom from Chinese A2/AD capabilities as possible,” Wallace said.
Japan’s presumed counter-A2/AD ambitions are restricted by Article 9 of its constitution, which forbids the nation from using military forces to settle international disputes, and the ban on “collective defense,” or the right to use force to aid an ally who is under attack.
This has led to a situation in which the Japanese and US navies can fight together but only under independent commands. Further, the ban on collective defense means that, strictly speaking, the Japan Self-Defense Forces cannot directly protect US forces from attack. In a joint operational air-sea battle, Japan would have to attack Chinese forces for the purpose of Japan’s self-defense not for the protection of US forces. Japan has defined its defense perimeter at 1,000 nautical miles, which means Japanese ships would likely defend US ships attacked in international waters within this expansive area.
“In other words, the Japanese protection of US forces fighting in aid of Japanese defense is the same as Japan fighting for Japan’s defense,” Wallace said. “The tricky issue comes when we go outside of Japan’s defense perimeter, say into the South China Sea. In which case, the issue becomes legally clouded.”
Beyond improving its ASW capabilities and building its resilience to electronic and cyber warfare attacks, there is little else Japan can do to counter a Chinese A2/AD strategy within the confines of Article 9.
As it stands, “Japan cannot strike at Chinese offensive capabilities such as cruise missiles, etc.,” Manicom said. “That’s not to trivialize how important ASW is to countering China’s A2/AD strategy.”