Japanese citizens would have 10 minutes to prepare for a North Korean nuclear attack

Missile 'will not take long to reach Japan,' says government

The Government has been briefing local authorities on what they should do if a missile lands in their area and urging them to hold evacuation drills (AFP/Getty Images)

Japanese citizens will have just 10 minutes to prepare a North Korean ballistic missile attack, authorities in the country have warned.

In the event of an attack, a document posted on the country's civil protection site advises people to find the strongest concrete building possible or go underground.

Then they should then take cover under tables and stay away from windows, it says.

A ballistic missile would likely take around 10 minutes to travel 1,600 km (1,000 miles) from its launch pad in North Korea to Okinawa, it adds, citing a launch in February last year which took that length of time to fly over the Japanese island.

The warning comes as tensions ratcheted up between North Korea, its Asian neighbours and the US. ​The secretive communist state test-fired four ballistic missiles last month, three of which landed in Japan’s exclusive economic zone in the Sea of Japan, just off the coast of the country.

It has subsequently emerged that the country's civil defence website had 5.7 million visitors in the first 23 days of April — more than 14 times the usual monthly traffic.

Japan's early-warning system, which issues missile strike alerts to the population via loudspeaker and telephone has come under increased scrutiny amid the rising tensions.

In 1998, North Korea demonstrated that its missiles were capable of reaching Japan when it fired a missile to launch a satellite across Japanese territory that landed in its economic zone on the Pacific Ocean side.

Japan's government has been briefing local authorities on what they should do if a missile lands in their area and urging them to hold evacuation drills.

Sales of nuclear shelters and radiation-blocking air purifiers have also surged in recent weeks.

Meanwhile, in the US, every member of the Senate was called to a White House briefing on the threat posed by North Korea last week.

Donald Trump triggered speculation he was planning a response in the event of another nuclear test by Pyongyang when he made hastily scheduled calls to Japan’s Prime Minister, Shinzo Abe, and China’s President, Xi Jinping, over the weekend.

Mr Trump later told UN Security Council ambassadors “the status quo” was not acceptable and said the council must be ready to impose new sanctions.