TOKYO • Japan is leaning towards choosing the Aegis Ashore missile defence system over the Terminal High Altitude Area Defence (Thaad), given missile launches by North Korea, government and ruling party sources told Reuters.
Japan has been looking into introducing a new missile defence layer - Thaad or the Aegis Ashore, a land-based version of the Aegis system developed for warships.
The government now favours the Aegis Ashore system over Thaad as it has a wider coverage area, which would mean fewer units needed to protect Japan, and also because it is cheaper, said three government and two ruling party sources.
The sources, who spoke to Reuters last week, declined to be identified as they are not authorised to speak to the media on the topic.
An Aegis Ashore unit costs about 70 billion yen (S$867 million) to 80 billion yen, while a Thaad unit costs more than 100 billion yen, they said.
The introduction of Aegis Ashore would help to reduce the burden of round-the-clock vigilance shouldered by Japanese warships with the Aegis system, they said.
An Aegis-equipped destroyer is said to require a crew of about 200 to 300 people, Japan's Yomiuri Shimbun reported. But one Aegis Ashore base can be run with about 10 per cent of that manpower.
The Defence Ministry plans to decide by summer on the new system, which is expected to be introduced several years later, said Yomiuri.
The country now has a two-stage missile defence system - Standard Missile-3 interceptor missiles launched from Aegis-equipped destroyers will intercept missiles in outer space at a maximum altitude of 500km. If the missiles are not blocked, they will next be met by Patriot Advanced Capability-3 (PAC) surface-to-air missiles at about a dozen kilometres above the ground.
A new system would mean three stages of interception - Aegis-equipped destroyers from the sea, Aegis Ashore on land, and PAC missiles - thus improving Japan's ability to block missiles.
The Defence Ministry has stepped up discussions to roll out new defence equipment, after a proposal to reinforce the country's defence against ballistic missiles.
The Aegis Ashore system, which would be installed in a fixed place on land, will have missile defence equipment and equipment that can deal with attacks by warplanes and cruise missiles otherwise seen on Aegis-equipped destroyers.
The Thaad system is seen to be less cost-effective as six bases are needed for it to cover the whole of Japan, compared with two Aegis Ashore bases, Yomiuri reported.
Likely protests from China and Russia if Japan were to deploy Thaad have also nudged Tokyo towards the Aegis Ashore system.