Theresa May has been told to "duck and cover" if North Korea launches another missile during her three-day trade trip to Japan.
The Prime Minister and other members of her delegation - which is hoped to pave the way for stronger relations between the two countries after Brexit - were told to deploy the decades-old tactic if the 10-minute warning rings out during their visit, according to the Times.
Before embarking on her trip May branded Pyongyang's latest provocation - in which a missile flew over Japanese territory before crashing into the sea - "reckless" and illegal. She plans to discuss the growing threat with Japanese Prime Minister Shinzo Abe during her three-day stay.
The projectile passed over the Tohoku region of northern Japan and landed 1,180 km east of Cape Erimo on Hokkaido. The Japanese government told people in the city to take cover.
May is also expected to be grilled by officials eager to gain clarity over Brexit and what it means for Japanese businesses.
Shinichi Iida, minister for public diplomacy at the Japanese embassy, told the Today programme he was “concerned”
“It is no secret the Japanese government and also as well as lots of Japanese companies preferred the situation in which the UK would remain within the EU," Iida said.
“However, what Japanese businesses are expecting in my view is the clarity and the predictability over the process to come, particularly the recent agreement within the UK government for the provisional period will be a very important factor because it will give the time and adaptability for the Japanese companies to adjust to a new environment after Brexit.”