The government is planning to acquire a greater range of ship-borne interceptors, upgrading two of Japan’s six Aegis ships and building two more. It is also considering buying a U.S. land-based high-altitude interception system.
The Defense Ministry plans to develop an improved version of the SM-3 interceptor rockets carried by Aegis vessels and is examining the U.S. military’s ground-based Terminal High Altitude Area Defense system, known as THAAD.
This comes after North Korea sent a missile — which it dubbed a space rocket — on a trajectory that took it more than 2,000 km on Feb. 7. The launch mirrored one Pyongyang carried out in December 2012.
Four of the Maritime Self-Defense Force’s six Aegis destroyers are currently equipped with SM-3 interceptors. The ministry will upgrade the remaining two by fiscal 2018 and bring them into full compatibility.
In addition, the ministry will procure two more Aegis ships by fiscal 2020 to increase the total to eight.
The current SM-3 interceptors are based on the so-called Block 1A system. Japan and the United States are jointly developing the Block 2A system, which will has an increased interception range.
The current system requires the deployment of three Aegis ships at any one time to provide total coverage for the nation, while only one or two Block 2A-equipped Aegis destroyers would be needed, informed sources say.
Japan’s current two-tiered defense system calls for first trying to shoot down a missile with SM-3 interceptors at an altitude of more than 100 km. If that fails, the second line of defense is firing PAC-3 Patriot rockets as the incoming missile nears its target. The Patriot system has a range of 20 km.
The PAC-3 system alone is insufficient to shoot down medium-range ballistic missiles such as North Korea’s Nodong at low altitudes, because at speeds of 3 to 7 km per second upon atmospheric re-entry such rockets are traveling too fast, the sources said. Nodong missiles have a range of about 1,300 km and can therefore strike Japan.
Meanwhile, the Defense Ministry is studying introducing the THAAD system, which intercepts missiles when they re-enter the atmosphere. This would supplement the PAC-3 system and give the nation a three-tiered missile defense.
The ministry is conducting research on THAAD, including the system’s capabilities and running costs.
THAAD comprises a launcher vehicle and a mobile X-band radar, which can reportedly detect an object as small as a baseball from a range of 1,000 km. It can only be deployed in certain locations, such as on a coast, because the radar has a strong output.
The U.S. Defense Department earlier studied selling two THAAD units, including radars and 150 interceptor missiles, to Qatar. The price was equivalent to more than ¥500 billion.