U.S. special representative for North Korea policy Stephen Bosworth says anything the North does in the area of nuclear development is of immediate concern.

Bosworth’s remark comes following the North’s Friday claim, carried by its official Korean Central News Agency, that it has successfully conducted uranium enrichment.

Pundits say the North’s announcement may have been voiced over frustration with the Obama administration’s refusal to face Pyongyang in one-on-one denuclearization talks.

Bosworth stressed again on Friday that the United States would hold direct talks with North Korea only within the context of the six-party process.

The top envoy visited Beijing Thursday and held meetings with China’s Foreign Minister Yang Jiechi and its top nuclear envoy Wu Dawei.

He arrived in Seoul on Friday afternoon.