North Korean leader orders the development of a nuclear arsenal and new intercontinental missiles

North Korean leader Kim Jong Un has ordered the development of new intercontinental ballistic missiles and a larger nuclear arsenal to counter US-led threats, state media said on Sunday, amid escalating tensions with South Korea.

During a meeting of the ruling Workers' Party, Kim stressed the need to ensure "overwhelming military force" to defend North Korea's sovereignty and security.

The meeting came amid tensions on both sides of the border over North Korean drones penetrating South Korean airspace last week and Pyongyang firing several missiles, including intercontinental ballistic missiles.

South Korean President Yoon Sok-yol, during phone calls with military chiefs, called for "raising the degree of psychological readiness and operational training" to ensure a response to any provocations from North Korea, according to a statement from his office.

Kim accused Washington and Seoul of trying to "isolate and strangle" Pyongyang with the continued deployment of US nuclear attack capabilities in South Korea, describing it as "unprecedented in human history".

North Korea's official KCNA news agency said Kim pledged to develop another ICBM system whose "main task is a rapid nuclear counter-strike" as part of a plan to boost the country's nuclear force.

"The current situation calls for redoubled efforts to build up military power and turn it into an overwhelming force... in response to the troubling military moves by the United States and other hostile forces," KCNA quoted Kim as saying.

Under the plan, North Korea will also launch its first military satellite "as soon as possible," KCNA said, accelerating its efforts to build a spy satellite as preparations enter their final stages.

Follow our latest local and sports news and the latest political and economic developments via Google news