North Korea vowed on Friday to strengthen its nuclear deterrent because of what it called Washington's continuing hostile policy, as a US envoy toured the region to try to restart disarmament talks.
"The study of the policy pursued by the Obama administration for the past 100 days since its emergence made it clear that the US hostile policy toward the DPRK (North Korea) remains unchanged," a foreign ministry spokesman said.
"The DPRK will bolster its nuclear deterrent as it has already clarified," the spokesman said in a statement on the communist state's official media. Stephen Bosworth, Washington's special envoy for North Korea, arrived in China on Thursday and said he is willing to hold talks with Pyongyang. He was due in South Korea later on Friday.
After the UN Security Council condemned its April 5 rocket launch and tightened sanctions, the North announced it was quitting six-party nuclear disarmament talks and restarting a programme to make weapons-grade plutonium.
Last week it vowed to conduct a second nuclear test as well as ballistic missile tests unless the UN apologises for its actions. The six-way talks group the two Koreas, the United States, China, Russia and Japan.
"Nothing would be expected from the US, which remains unchanged in its hostility toward its dialogue partner," the North said, denying suggestions that its actions are aimed at pushing Washington to hold direct talks.
"The measures... are aimed not to draw attention of someone and have dialogue with it but to defend the security of the country and the sovereignty of the nation."
Bosworth will also visit Japan and Russia next week but has no current plans to visit Pyongyang. The North appears to have timed its message with Bosworth's visit, said Yang Moo-Jin of Seoul's University of North Korean Studies.
"North Korea is telling Bosworth, 'We won't move the slightest bit as long as the US keeps its current policy. If you want to talk with us, show us some change,'" Yang told Yonhap news agency. South Korea's Chosun Ilbo newspaper Thursday reported brisk activity at the site where the North carried out its first atomic test in October 2006.
The North says its April launch put a satellite into orbit for peaceful research purposes. Other nations saw the exercise as a disguised test of a ballistic missile. The North complained that Obama had called for punishment for the launch and termed it a challenge and a provocation.
It said Secretary of State Hillary Clinton "is repeating such malignant vituperation let loose by the preceding government as slandering the system in the DPRK as 'tyrannical' and 'rogue regime' and the like." Pyongyang also criticised the Obama administration for going ahead with major joint military exercises with South Korea in March.
The exercises "threatened our security seriously," it said. In Beijing on Thursday Bosworth expressed willingness to talk. "The United States reiterates its desire to engage both multilaterally and bilaterally with North Korea," he said after meeting Chinese Foreign Minister Yang Jiechi.
Clinton said in Washington that the United States and its negotiating partners may have to "show some patience" before the nuclear disarmament talks can resume. Speaking at a press conference with Russian Foreign Minister Sergei Lavrov, she said both Washington and Moscow want to try to get the North Koreans back to the six-party framework.