Military pressure around Japan continues to rise, with one of its coasts facing one of the planet’s most tense and coveted seas. In the country’s plans, the aim was to build a fixed land-based anti-missile containment system. But that idea has evolved into an immense floating wall, far more capable: two 12,000-tonne giants nearly 200 meters long.
Japan is constructing two colossal ships using the same technology as the scrapped fixed Aegis Ashore bases, conceived for air defense, anti-ship, and anti-missile defense: the Aegis System Equipped Vessel (ASEV). Under their hull, they will house almost 130 vertical missile launch cells, in addition to a powerful radar and the Aegis combat system. They are also designed to accommodate new weapons to adapt to emerging threats.
12,000-Ton Giants with Enormous Radars and an Arsenal Beneath Deck
These Aegis-equipped warships are far larger than a conventional destroyer. And compared to fixed bases they have a clear advantage: they are a mobile shield that can be moved wherever needed. Their dimensions are staggering: the first one under construction measures 189 m in length, 25 m in beam, and 12,000 tonnes of displacement. To put it in context, the already gigantic Maya-class destroyers are 170 m long and can displace around 8,200 tonnes.
This first ASEV began assembly at Mitsubishi Heavy Industries’ (MHI) shipyard in Nagasaki in July 2025, and the objective is for the Kaijō Jieitai (Japan’s Maritime Self-Defense Force) to have it in the fleet before the end of fiscal year 2027 (between April 2027 and May 2028). The second, launched in Yokohama in February 2026, should come online in the following fiscal year.
Advanced radars. By the end of August, the ASEV still under conception in Nagasaki, while very advanced, had its enormous main mast installed where four gigantic AESA antennas from Lockheed Martin’s AN/SPY-7(V)1 will be integrated later. Each antenna stands about 4.3 meters tall and, according to the Ministry of Defense, the SPY-7’s tracking capability is five times greater than that of the SPY-1 fitted on current Japanese destroyers, especially for ballistic missiles and complex trajectories. Moreover, its elevated position improves the line of sight, making it more capable against missiles, but also against threats that fly low, such as drones or cruise missiles.
Hundreds of missiles. The ASEV ships also stand out for their substantial armament capacity. Their main attraction is the 128 vertical launch tubes (Mk 41 Vertical Launching System – VLS -) concealed beneath the deck. This modular system allows combining different missiles, such as the SM-3 Block IIA for ballistic missile defense or the SM-6, among others. In sheer numbers, it surpasses the 112 cells aboard the Chinese Type 055 destroyer, and far outstrips the Maya-class destroyers.
Japan’s 2026 Defense White Paper
This will be only the beginning. In 2032, the Defense Ministry expects to equip also American Tomahawk cruise missiles and the extended-range version of Japan’s Type 12. With Tomahawks, it will be able to strike land and naval targets at about 1,600 km. That means it could neutralize missiles as well as strike launch positions from which they are fired. Additionally, Japan plans to deploy high-energy laser weapons to combat drones, and these ships have the space and power to integrate them.
A Floating Wall Against China and North Korea
The decision to create this immense floating shield comes at a time when the militarization of Japan’s neighbors shows no sign of slowing down, looking toward tense zones. For example, China has notably expanded its naval, air, and missile capabilities, and heightened its activity around the Senkaku Islands in the East China Sea, administered by Japan but claimed by Beijing.
China has long been increasing its military presence in both the South China Sea and the East China Sea, rapidly building artificial islands on reefs that dangerously resemble new air bases. The People’s Republic mobilized more than 3,000 fishing boats between December and January off the Japanese coast, in a strange formation, creating a kind of ‘Great Fishing Wall’ of 300 km. The so-called gray zone is becoming a theater of maritime pressure.
Joining China’s escalation is North Korea. Pyongyang has spent decades amassing a broad arsenal of ballistic missiles that Japan believes could reach all of its territory. These new ASEVs thus arise in a context of multi-pronged defense, as a first barrier of containment at sea: ships able to stay deployed for long periods, with high early-warning capabilities and, if necessary, capable of intercepting air and ballistic threats with their Aegis systems.
Images | @kensakai9310 on X, Japan’s Ministry of Defense
