North Korea on Wednesday fired a missile from a submarine that flew for 500 km towards Japan, its latest in a series of weapons test that has earned it global isolation and sanctions. As usual, this launch was in violation of sanctions imposed on the dictator-ruled country, which is always looking to improve and showcase its technological prowess, especially in the field of weaponry.

Sources from South Korea — a country that keeps close tabs on its northern neighbour over fear of being attacked any time — said the submarine fired the missile at around 5:30 a.m. local time from what has been revealed by satellite imagery to be a submarine base in the city of Sinpo.

Japanese Prime Minister Shinzo Abe told reporters that this was the first time a missile fired by North Korea had managed to enter Japan's air defence identification zone (ADIZ), which is used in the maintenance of air security. "This is a threat to Japan's security and an unforgivable reckless act that significantly damages the peace and stability of the region," Abe said.

This was a significant step-up from the previous attempt by North Korea three weeks ago, when the missile had landed near Japanese waters.

That the missile lunched on Wednesday had reached this far is being seen in the global defence and intelligence establishment as a clear sign that North Korea, under current leader Kin Jong-un, was making quite a bit of progress in the development of submarine-launched ballistic missile (SLBM) technology.

The latest act of aggression from North Korea comes just two days after the United States and South Korea began a joint military drill, amid threats of a nuclear attack from Kim Jong-un's regime. North Korea considers such joint military drills preparation for invasion, and had threatened a pre-emptive nuclear strike if the U.S. and South Korea chose to go ahead with it.

North Korea had conducted a nuclear test in January this year, which had isolated it even more from other countries.