North Korean leader Kim Jong-Un has ordered further nuclear explosion tests in order to test warheads that have been newly developed by his scientists, state media reported Friday.
While overseeing a ballistic missile test-firing on Thursday, Kim underscored the importance of performing "more nuclear explosion tests to estimate the destructive power of the newly produced nuclear warheads", the North's official KCNA news agency said.
State media on Wednesday had published photos of Kim visiting nuclear technicians and standing next to what was claimed to be a miniaturised nuclear warhead.
During the visit, he claimed that his scientists had achieved the process of shrinking warheads to a size capable of fitting on a ballistic missile. If confirmed, this step would increase the threat to South Korea, other countries in the region and eventually, the US mainland.
North Korea launched two short-range ballistic missiles on Thursday, which traversed the eastern part of the country before falling into the East Sea (Sea of Japan), according to the North Korean official KCNA news agency.
That drill was part of a military exercise including a nuclear counter-strike against invading forces.
The exercise was clearly a response to ongoing large-scale, South Korea-US military drills that Pyongyang views as provocative rehearsals for invasion.
The target was to simulate conditions for “exploding nuclear warheads from the preset altitude above targets in the ports under enemy control of foreign aggressor forces", the agency said.
Watching the exercise, Kim repeated an earlier threat to launch an immediate nuclear attack if menacing South Korea-US drills should harm "even a single tree or a blade of grass" on North Korean territory.
"I will issue a prompt order to launch attack with all military strike means," he said.
Military tensions between North Korea and neighbouring countries have been on the rise since the North performed its fourth nuclear test in January.
The country also launched a long-range rocket in February, sparking international reaction as well as opening way for additional sanctions from South Korea.
The UN Security Council approved a US-drafted resolution to impose tougher new sanctions on Pyongyang following its fourth nuclear test on January 6 and rocket launch on February 7.
UN Secretary-General Ban Ki-moon on Thursday expressed grave concern over the tensions, and called on Pyongyang to avoid any further "destabilising acts such as today's launch of two missiles.”
North Korea often fires short-range missiles when tensions rise, particularly during annual US-South Korea drills, which it claims are preparations for an invasion.