What’s behind the sudden increase in missile tests from North Korea?

With six launches in 12 days, North Korea is flexing its muscles and taking advantage of geopolitical turmoil across the world

Millions of residents of northern Japan will have felt a sense of deja vu on Tuesday morning when they were alerted to a North Korean missile flying overhead. Five years earlier, they had twice been shaken from their slumber by Japanese government warnings to seek shelter after missile launches by Pyongyang.

The intermediate-range missile involved in this week's test was far from buzzing the rooftops of Hokkaido farmhouses - it flew at an altitude of 1,000km as it made its way to the Pacific Ocean, where it splashed down, without incident, more than 3,000km east of Japan.