Japan and the US plan to bolster their defenses against hypersonic threats by teaming up to develop a hypersonic missile interceptor and satellite constellation early warning system against rising threats from China and North Korea.
This month, Nikkei reported that the US and Japan have opened discussions on the joint development of what Japan’s Ministry of Defense (MOD) calls the world’s first practical application of an interceptor missile for hypersonic projectiles.
The report notes that the two sides aim for the new interceptor to be able to maneuver in response to projectiles flying at high speed with changing velocity at low orbit. It notes that if the interceptor is developed, it is expected to be able to intercept hypersonic projectiles before they near the point of impact.
The Nikkei report says that the US and aim to cooperate to enhance detection and tracking, with the two allies planning to work on a satellite constellation that processes data from many satellites for high accuracy and early detection.
Japan faces significant missile threats from China and North Korea. Asia Times noted in August 2022 that China has 1,900 ground-launched intermediate-range ballistic missiles and 300 intermediate-range cruise missiles capable of striking Japan.
Similarly, North Korea has hundreds of ballistic missiles that bring Japan within range. China and North Korea have developed hypersonic weapons designed to evade current missile defenses, such as Patriot and Aegis, which Japan currently extensively uses.
In the aftermath of former US Speaker of the House of Representatives Nancy Pelosi’s controversial visit to Taiwan last August and the ensuing Chinese military drills and ballistic missile firings around the self-governing island, multiple media outlets reported that five Chinese ballistic missiles landed inside Japan’s exclusive economic zone (EEZ), with four missiles flying over Taiwan before impact.
Former Japanese minister of defense Nobuo Kishi noted that the incident was the first time Chinese missiles landed inside Japan’s EEZ. Kishi mentioned that the missile impacts were a grave issue that impacted Japan’s national security while saying that the Japanese government delivered a diplomatic protest to China.
Asia Times reported in November 2022 that Japan plans to overhaul its Type 03 surface-to-air missile (SAM), first introduced into service in 2003, to shoot down hypersonic glide vehicle (HGV) weapons.
Japan aims to upgrade the Type 03’s launch software by 2026 and start production of the upgraded missiles by 2029, with the type first upgraded in 2017 to improve its performance against low-flying and fast-moving targets.
The new upgrades will give the Type 03 the capability to detect, track and predict the flight path of hypersonic weapons, as Japan’s current missile defenses are likely insufficient against such threats.
It is still being determined, however, if those upgrades would be effective as hypersonic weapon technology is advancing quickly.
Asahi Shimbun reported on November 2022 that Japan’s MOD plans to deploy a missile early warning satellite constellation consisting of 50 satellites in low-earth orbit to track hypersonic missiles.
The report says the satellites will make frequent passes on specific targets, giving Japan additional time to assess whether enemy military units are moving into action.
It also mentions that once the satellite system is in place, a verification test will be held to spot and track hypersonic missiles that keep changing course as they fly over speeds of Mach 5.
In addition, Asahi Shimbun says that Japan’s MOD wants to specify the satellite constellation framework in the next Mid-Term Defense Program spanning fiscal 2023-2027.
Japan’s Type 03 SAM upgrades and planned missile early warning satellite constellation may get a boost from US technology in the Glide Phase Interceptor program, which faces significant funding issues.
In addition, the US may lend Japan expertise in building its satellite early warning system, following a two-tier concept featuring LEO and medium-earth orbit (MEO) satellites.
Japan has multiple projects to bolster its missile defenses. Asia Times reported in August 2022 that the Japanese MOD plans to spend US$7.1 billion on two AESV destroyers armed with a sea-based version of Aegis Ashore.
The AESV is planned as a 20,000-ton warship measuring 210 meters from stern to bow and with a maximum width of 40 meters, making it comparable in size to an aircraft carrier.
Reuters reported in October 2022 that the US State Department had approved the sale of as many as 32 Standard SM-6 Block I missiles and related equipment to Japan, with the proposed sale aimed at improving Japan’s air and ballistic missile defense capabilities against potential adversaries in the region.
However, when faced with a highly-lofted trajectory ballistic missile attack, the AESV may not be effective as missile defense radars can lose track of the target once it reaches its apex.
This delay causes the interceptor missiles to miss the target as they cannot adjust their trajectory in time. The hostile missile’s constant acceleration makes it even more challenging for the interceptor missiles to catch up and hit the target at the correct angle.
Maintaining AESVs on stations around the clock may prove difficult compared to land-based sites that can remain at constant readiness.
Additionally, Japan’s proposed large missile defense destroyers may face survival challenges. If built, these vessels will likely be prioritized for attack by China and North Korea’s anti-ship missiles and hypersonic weapons.
In February 2022, Asia Times reported that while the SM-6 Standard can destroy ballistic missiles flying at hypersonic speeds, its effectiveness against maneuvering hypersonic targets is questionable.
In 2021, a US Aegis warship attempted to intercept a medium-range ballistic missile with two SM-6 Dual missiles. The missiles failed to hit the target despite their successful testing against conventional ballistic missile threats in 2015 and 2017.
Apart from upgrading its long-serving Type 03 SAM, designing AESV destroyers and procuring additional SM-6 interceptors from the US, Japan has also looked into experimental technologies for missile defense.
In January 2022, Asia Times reported that Japan’s MOD plans to develop railgun technology to counter China and North Korea’s hypersonic missiles, a weapon that can potentially fire a projectile at six times the speed of sound using electromagnetic energy.
Railguns may have several advantages over missile-based defenses such as hypersonic shot velocity and smaller projectile cost versus missile interceptors.
Since railgun projectiles rely on kinetic energy rather than explosives to destroy their targets, they are safer to handle and reduce strain on logistics, with more rounds capable of being stored in land or ship-based batteries. Moreover, railguns are not affected by line of sight or weather conditions, unlike laser weapons.
However, some of the main challenges hounding railgun technology include finding a power source that can generate the massive amount of electricity needed for each shot. Electromagnetic “rails” are also known to erode and burn out after relatively few shots.