North Korean leader Kim Jong Un called for the "rapid expansion” of his country’s nuclear weapons program, escalating tensions with the U.S. and South Korea as the allies conduct joint military drills that Pyongyang views as a prelude to war.

Visiting the recently launched destroyer Choe Hyon, Kim said the security environment around the country requires North Korea to make a "rapid expansion of nuclearization” and speedily develop its naval forces, the official Korean Central News Agency reported Tuesday.

"Kim Jong Un said that the U.S.-ROK intensified military nexus and the muscle-flexing are the most obvious manifestation of their will to ignite a war and the source of destroying the peace and security environment in the region,” KCNA reported. ROK stands for South Korea’s official name, the Republic of Korea.