TOKYO -- The Japanese government is considering three main options to replace the halted Aegis Ashore land-based missile shield, but all carry a certain amount of risk.
A recommendation approved Friday by defense-related panels in the ruling Liberal Democratic Party urges the government to quickly come out with "concrete proposals" to fill the gap left by the absence of the land-based missile shield, which was put on hold last month due to cost concerns.
The government is looking at three main possibilities: building a radar system on land that would detect incoming missiles to be shot down by ship-based interceptors, adding more Aegis-equipped ships to the existing fleet, and building a large offshore structure to house both the radar system and interceptors.
Each of these options could use the 180 billion yen ($1.7 billion) in equipment that Japan has already agreed to buy for Aegis Ashore. But all three proposals involve trade-offs.
A remote radar system would let the government install the interceptor battery in a location that would minimize the risk of booster rockets falling on residential neighborhoods -- one of the factors that sank the Aegis Ashore project. But the technology is still experimental, and any disruptions to communication between land and sea would hinder the system's ability to shoot down missiles.
Expanding Japan's fleet of Aegis ships would not entail the operational risks involved in adding an entirely new layer to the country's missile shield. But these vessels are expensive to build, and 600 crew members would be required to staff just two, further straining the chronically understaffed Maritime Self-Defense Force.
An artificial island, meanwhile, would be vulnerable to threats such as torpedoes and terrorist attacks. Many in Tokyo see this proposal as unsuitable for what would be a keystone of the country's missile defense system.
The government will set out a policy direction in September based on factors including effectiveness, cost and staffing.