North Korea laughs off US sanctions, leader says ‘it is meaningless’

North Korea said on Sunday a push for further sanctions following its fifth and biggest nuclear test was “laughable”, and vowed to continue to strengthen its nuclear power.

The isolated state on Friday set off its most powerful nuclear explosion to date, saying it had mastered the ability to mount a warhead on a ballistic missile, ratcheting up a threat that its rivals and the United Nations have been powerless to contain.

A U.S. special envoy met with Japanese officials on Sunday and said later the United States may launch unilateral sanctions against North Korea, echoing comments by U.S. President Barack Obama on Friday in the wake of the test.

“The group of Obama’s running around and talking about meaningless sanctions until today is highly laughable, when their ‘strategic patience’ policy is completely worn out and they are close to packing up to move out,” state-run KCNA news agency cited a North Korean foreign ministry spokesman as saying in a statement later on Sunday.

“As we’ve made clear, measures to strengthen the national nuclear power in quality and quantity will continue to protect our dignity and right to live from augmented threats of nuclear war from the United States,” KCNA added.

Earlier, the South’s Yonhap news agency reported South Korea’s military had a plan to use its missiles to “decimate” areas of Pyongyang if there were signs the North was about to launch a nuclear attack, quoting a source in the military.