GETTY Japan is stepping up security measures following sarin gas threats from North Korea

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Concerns about a possible gas attack in Japan have grown after prime minister Shinzo Abe told a parliamentary session in April that North Korea may have the capability to deliver missiles equipped with sarin nerve gas. His remarks saw a sudden demand for nuclear shelters, with one small company receiving the equivalent of a year's worth of orders in the space of just three weeks. Multiple missile tests conducted by North Korea since the start of the year, including the recent launch of an intercontinental ballistic missile, have sparked intense alarm in Japan, creating a flurry of civil defence activity not seen in the country since World War Two.

At least nine Japanese towns have conducted evacuation drills since North Korean missiles landed in the sea within Japan’s exclusive economic zone in March. The peaking interest in home shelters also came after the government issued a 30-second warning on primetime television, imploring Japanese citizens to seek shelter in sturdy concrete buildings or flee underground in the event of an attack. The warning advised those stranded in their homes to hide behind sturdy objects, lie face down on the floor and to stay away from windows. Such advice has unwittingly caused the entire nation to panic, and seek to create a safe place to flee if North Korea struck.

GETTY Kim Jong-un celebrates the successful launch of an intercontinental ballistic missile

Seiichiro Nishimoto’s shelter manufacturing company has seen inquiries rise dramatically since the start of the year. The Osaka-based firm has sold more than a dozen shelters in the past two months – twice as many as it used to sell in a whole year. The 80-year-old businessman said: “Most of our customers are worried about nuclear fallout from a North Korean attack. “I think we should have shelters everywhere in Japan. People complain about the cost, but the smallest ones are no more expensive than a family car.”

Mr Nishimoto added he had taken three orders in just the past week, and was in talks with the owners of an apartment block to install a communal shelter. Nobuko Oribe, the director of Oribe Seiki Seisakusho, said her firm had received twice as many orders in April and May than during the whole of 2016. She added: We went through Hiroshima and Nagasaki, and now, 70 years later, people are worried about nuclear attacks again.”

GETTY Thousands of North Koreans took part in elaborate celebrations following the Hwasong-14 ICBM launch

The firm, which was founded by Ms Oribe’s grandfather just after the Cuban missile crisis, offers a range of shelters - including one shelter for up to 13 people costing £171,028 - or 25 million Japanese Yen. The company has also sold out of its Swiss-made air purifiers, said to keep out radiation and poisonous gases.

First images of THAAD missile launch test Thu, July 13, 2017 Explosive first images show Terminal High Altitude Area Defence (THAAD) defence system shooting down an intermediate-range ballistic missile (IRBM). Play slideshow Missile Defence Agency 1 of 5 Air launch intermediate range ballistic missile target

Critics of Japan’s conservative Prime Minister have accused him of exploiting fears of a North Korean war to justify record defence spending and divert focus from controversial plans to revise Japan’s “pacifist” constitution. However, there are those that say the fears aren’t entirely misplaced. According to Japan’s government, it would take only 10 minutes for a missile to cover the 995-miles between the North Korean launch site and a US military facility based on the southern Japanese island of Okinawa.

GETTY The Hwasong-14 missile was successfully launched by North Korea earlier this month