North Korea leader Kim Jong-un has ordered his military to produce solid-fuel engines and ICBM warheads, thus bolstering the country's ballistic missile programme.
The photos of Kim visiting the institute were also released by North's official Korean Central News Agency, which showed a conceptual diagram for a missile called the Pukguksong-3 which appears to be the latest in its Pukguksong, or Polaris, series. It was identified as an "underwater strategic ballistic missile," indicating that it would have a longer range than the Pukguksong-1.
Kim gave his instructions to produce "solid-fuel ballistic missile", during a visit to the Chemical Material Institute of the Academy of Defence Science, the North's official Korean Central News Agency said.
"He instructed the institute to produce more solid-fuel rocket engines and rocket warhead tips i.e. ICBM nose cones by further expanding engine production process and the production capacity of rocket warhead tips and engine jets," the news agency said of the visit.
Unlike liquid-fuel rockets, solid-fuel missiles do not have to be loaded with fuel just before the launching, a process that can take up to an hour and make the missile vulnerable to a pre-emptive strike. Such missiles are also easier to transport and hide, the New York Times reported.
The news was released just hours after as U.S. President Donald Trump announced that Kim "has started respecting" them during a rally at Pheonix, Arizona
"It appears that the North is trying to tell the world that its re-entry and solid-fuel technologies are no longer experimental, but have reached the stage of mass production," the New York Times quoted Kim Dong-yub, a defense analyst at the Institute for Far Eastern Studies at Kyungnam University in Seoulas, as saying.
"Though whether that's credible is another matter."
The tensions between North Korea and the United States escalated when the Pyongyang military presented a plan to Kim Jong-un of firing four missiles towards the U.S. Pacific territory of Guam.
Meanwhile, South Korean President Moon Jae-in indicated that the North had not built a reliable ICBM.
"I think the red line is when the North completes an ICBM and weaponizes it by loading it with a nuclear warhead, and it is inching toward that critical red line," Moon said in a televised statement, warning that additional missiles tests by the North would invite tougher and "unbearable" sanctions from the United States.