The government cancelled the deployment of the Aegis Ashore missile defense systems because “it cannot be ensured that the boosters will fall inside the designated training area after detachment.” Actually, the government had never looked into whether the boosters could fall outside the training area. This was revealed in a Defense Ministry report obtained by Lower House member Keiji Kokuta of the Japanese Communist Party.

The 7,000 page report titled “Basic plans and other procedures for (30) candidate sites: Mutsumi training area” was released by the Ministry of Defense (MOD) in May 2019. It examined the basic plans for the Mutsumi training area (Hagi City, Yamaguchi Prefecture) that included designating (1) a “managed zone” for magazine, fuel stores, and the Self-Defense Force’s housing compound and (2) an “operations zone” for magazine, radars, and vertical launch systems. This report was used to draft the explanatory documents distributed by the MOD to the Yamaguchi Prefectural Government and other parties concerned.

In answer to the concerns voiced by local residents that the boosters might fall on residential areas, the MOD has said since August 2018 that it will make sure that the boosters land in the training zone. However, the MOD report obtained by Kokuta did not mention “boosters” and did not consider the locations where they could land in connection with the placement of magazines and fuel stores.

Despite this, the information delivered to the prefecture by the MOD read, “We will take concrete steps to make sure that the boosters land in the training zones.” (Abridged)