Defence Minister Gen Nakatani outlined the new measure during a press conference in Tokyo on Tuesday, although no timeline for the deployment was given and the locations of the new radar units were not confirmed.
Experts suggest it is possible that the deployments may be of additional units to islands that already have radar capabilities, such as the outlying islands of Okinawa prefecture and Minamitori island, the most easterly point of Japan and close to where one of the Chinese fleets was seen operating at the weekend.
It is unlikely that radar will be placed on the disputed islands in the East China Sea, which are controlled by Tokyo but are claimed by Beijing, which refers to the archipelago as the Diaoyu Islands. Tensions are already high around the uninhabited islands, with Chinese coastguard vessels a near-constant presence within Japan’s territorial waters, and experts say any sort of military buildup would only inflame the situation further.

The atoll of Okinotorishima might be under consideration, although that could also prove to be contentious.
The island lies 1,080km south of Tokyo but only has 9.44 square metres of land above water, and that is only because it has been raised with concrete blocks. Nevertheless, the atoll is Japan’s most southerly point and enables Japan to claim an exclusive economic zone (EEZ) covering the surrounding 400,000 sq km of ocean.