Kim Jong-un calls latest missile test 'adequate warning' to U.S. and South Korea

North Korea said Wednesday that leader Kim Jong-un supervised a live-fire demonstration of newly-developed short-range ballistic missiles he said were intended to send an "adequate warning" to the United States and South Korea over their joint military exercises.

The announcement by Pyongyang's official Korean Central News Agency (KCNA) on Wednesday came a day after South Korea's military said it detected the North firing two projectiles that were likely ballistic missiles into the sea.

Seoul's joint chiefs of staff alerted reporters to the launches minutes before the North's foreign ministry denounced Washington and Seoul over the start of their joint exercises on Monday. The ministry's statement said the drills, which North Korea sees as an invasion rehearsal, leave the country "compelled to develop, test and deploy the powerful physical means essential for national defence."

North Korea's fourth round of weapons launches in less than two weeks came amid a standstill in nuclear negotiations and after U.S. President Donald Trump repeatedly dismissed the significance of the country's recent tests despite the threat the weapons pose to allies South Korea and Japan and to U.S. bases there.

U.S. National Security Adviser John Bolton reminded North Korea on Tuesday of its leader's pledge toTrump not to resume launches of intercontinental-range missiles, and warned it might pursue "a new road."

Experts say Trump's downplaying of the North's weapons display has allowed the country more room to advance its military capabilities as it attempts to build leverage ahead of negotiations, which could possibly resume sometime after the end of the allies' drills later this month.

KCNA said the launches early Tuesday verified the reliability and combat ability of the newly developed missiles.

The agency reported Kim expressed satisfaction and said the launches would "send an adequate warning to the joint military drill now underway by the U.S. and south Korean authorities."

Kim Dong-yub, an analyst at Seoul's Institute for Far Eastern Studies, said North Korea's decision to fly the missiles over its capital indicated it was confident about the reliability of the system. Kim, a former South Korean military official who had participated in inter-Korean military talks, said Kim Jong-un is making a measured effort to advance the North's military capabilities without allowing the nuclear negotiations with Washington collapse.

The projectiles travelled about 450 kilometres on an apogee of 37 kilometresat a maximum speed of above Mach 6.9 before landing in waters off the country's eastern coast, according to Seoul's joint chiefs of staff.

It said the projectiles showed similar flight characteristics to short-range missiles North Korea fired on July 25, which travelled about 600 kilometresduring launches the North described a "solemn warning" to South Korea over its plans to continue military drills with the United States.

South Korea's military had said the flight data of the July missiles showed similarities to the Russian-made Iskander, a solid-fuel, nuclear capable missile that is highly manoeuvrable and travels on lower trajectories compared with conventional ballistic weapons, improving its chances of evading missile defence systems. The North last week also conducted two test firings of what it described as a new rocket artillery system.