Kawasaki Heavy Industries Ltd announced on Thursday that it would make the first Japanese ventilators for underground shelters by 2026. This is as China, a neighbouring country, intensifies its military buildup while North Korea increases its arsenal of nuclear weapons and missiles.

"First and foremost, these are shelters to be used in disaster response for Japan's natural disaster prone country. They are also for shelters with defence purposes," said a Kawasaki Heavy spokeswoman.

It is expected that people will need to seek refuge in shelters at some point.

The Prime Minister Fumio Kishida recently stated that Japan is in the most severe security environment since World War Two.

Kishida said that what is happening in Ukraine "tomorrow" could also happen in East Asia.

The Kawasaki Heavy announcement came a day after Russian president Vladimir Putin signed an agreement with North Korean leader Kim Jong Un, which included a pledge of mutual defence.

Tokyo Governor Yuriko Koike has promised to build shelters in order to protect the 14 million residents of Tokyo from possible missile attacks.

Kawasaki Heavy has already developed expertise in controlling air flow in enclosed spaces as it is a submarine manufacturer. The ventilators that are planned will remove poisonous gases as well as particles from the air.

The spokesperson stated that the price of the ventilators has not yet been determined. (Reporting and editing by KiyoshiTakenaka, Rocky Swift and Miral Fahmy).