North Korea pledged to pursue its nuclear and ballistic missile programmes in defiance of the United States and its allies with a top envoy saying there is now a state of "semi-war" on the divided peninsula.

So Se Pyong, North Korea's ambassador to the United Nations in Geneva, made the statement on Friday as the US and South Korea held military exercises, which he said were aimed at the "decapitation of the supreme leadership of the DPRK [Democratic People's Republic of Korea]".

"If the United States continues, then we have to make the counter-measures also. So we have to develop and we have to make more deterrence - nuclear deterrence," So said in an interview with Reuters news agency.


READ MORE: North Korea ups tensions with new Sea of Japan firing


The ambassador's statement came as North Korea fired a new short-range missile into the sea on Friday and tried to jam GPS navigation signals in South Korea, according to Seoul officials. 

The latest missile firing took place just hours after US, South Korean and Japanese leaders agreed to work together to counter North Korea's nuclear threat.

US President Barack Obama joined South Korean President Park Geun-hye and Japanese Prime Minister Shinzo Abe on Thursday in vowing to ramp up pressure on North Korea in response to its recent nuclear and missile tests.

The three leaders warned they could take further steps to counter threats from Pyongyang.

'Slap in Xi Jinping's face'

In January, North Korea conducted its fourth nuclear test and in February launched a long-range rocket, angering even its closest ally, China, and prompting the UN Security Council to impose more sanctions on the reclusive state.  

South Korea and US military drills anger North

In Washington DC on Thursday, Chinese President Xi Jinping called for dialogue to resolve the "predicament" on the Korean peninsula.

In an interview with Al Jazeera, Einar Tangen, a political affairs analyst, said North Korea was increasingly defying its closest ally.

Pyongyang's latest action, he said, "is a slap to the face of Xi Jinping, a tremendous loss of face as he is meeting with Obama about nuclear issues".  

Meanwhile, So declared that North Korea is "going on our own way. [We are] not having dialogue and discussions on that", when asked whether Pyongyang felt pressure from Beijing.

So also said "the de-nuclearisation of the peninsula has gone", when asked about the resumption of stalled six-party talks on his country's nuclear programme.

Source: Al Jazeera and agencies