Japan is considering using a large ship as an alternative to the scrapped U.S.-made Aegis Ashore missile defense system as part of efforts to counter missile threats posed by North Korea, according to government sources.

The sources said Saturday the Defense Ministry is mulling the use of a 9,000-ton ship on which to mount the new Aegis system and allocate wider living space for crew. If realized, it would be the largest Aegis-equipped vessel of the Maritime Self-Defense Force.

File photo taken on the Hawaiian island of Kauai in January 2019, shows an Aegis Ashore missile-defense system at the Pacific Missile Range Facility of the U.S. Navy. (Kyodo)

The decision will be made around the year-end after the ministry receives an interim report in mid-November from two private firms familiar with the issue.

The government in June rolled back plans to deploy the anti-missile land complexes, saying the proposed deployment in the prefectures of Akita and Yamaguchi would put residents at risk of falling rocket boosters.

The ministry also said that modifying the technology would take years and cost too much.

As a substitute measure, the ministry is now focusing on two possible options -- remodeling private-sector vessels to mount the Aegis system and building dedicated maritime ships with the system.

The land-based Aegis to address the increased threat of North Korean ballistic missiles was originally aimed at helping reduce the workload of MSDF personnel who are under a severe shortage of manpower, by shouldering part of missile defense program from ashore.

With China stepping up its maritime activities in the East China Sea, patrols once out at sea could last more than a month for MSDF members, adding to concerns.

Japan, seeming adhered to a plan to introduce Lockheed Martin Corp.'s SPY-7 radar system which can be loaded onto sea-based facilities as well as onshore ones as in the original plan, looked at need for a larger ship because the new radar's height requires a vessel width greater than that of the conventional Aegis destroyers.

The proposed displacement of 9,000 tons exceeds that of the Maya, the largest Aegis destroyer to date, commissioned in March with a displacement of 8,200 tons.

But one ministry source expressed skepticism about the plan, calling it a "desperate measure" rushed by the sudden political decision to halt the original program.

That echoes some defense experts who doubt the ship-based option will provide Japan with the same levels of security since an offshore platform would be at risk in inclement weather.

Others voiced concern about rising costs in line with a possible increase in the ship size.

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