Infuriated by tough new UN sanctions, Pyongyang vowed earlier on Friday to abolish unilaterally all non-aggression pacts with South Korea in a latest installment of vitriolic attacks on Washington and Seoul this week.

“This kind of provocative rhetoric, these kinds of actions are just not going to improve conditions for the North Korean people,” US State Department spokesperson Victoria Nuland told reporters in Washington.

“They’re just going to increase tensions and it’s extremely regrettable,” she said.

Nuland also defended the new sanctions against N. Korea as they apply direct pressure on “those in the D.P.R.K. system who are taking the country in the wrong direction.”

The fourth set of UN sanctions, which was adopted on Thursday, is aimed at curbing the activities of North Korean institutions and individuals suspected of funneling money to the communist regime's nuclear and missile programs.

“If we don’t, as an international community, meet these provocations firmly, then we’re just giving license for the will of the UN Security Council to be flouted. We’ve got to be firm,” Nuland said.

The North's threats on Friday followed the statements it had made earlier this week, promising to scrap the armistice agreement that ended the Korean War in 1953, and threatening “pre-emptive” nuclear strikes on the United States and South Korea.

The White House immediately responded that “the United States is fully capable of defending against any North Korean ballistic missile attack,” even though most US experts do not believe Pyongyang has the technological capacity to carry out a nuclear attack on Washington.