The United States says it will continue implementing U.N. sanctions and exert pressure until North Korea returns to the denuclearization process.

During a news conference at the Foreign Press Center in Washington on Friday, U.S. Assistant Secretary of State for Public Affairs Philip Crowley said the United States will be supportive if North Korea wants to return to the process to take irreversible steps toward denuclearization of the Korean Peninsula.

In the meantime, Crowley said Washington is aggressively implementing the provisions of the United Nations Security Council Resolution 1874 and continuing to put pressure on the communist state.

Meanwhile, U.S. Assistant Secretary of State Kurt Campbell has arrived in Seoul for a three-day visit. During his stay, Campbell will meet with Deputy Foreign Minister Lee Yong-jun to discuss the North Korean nuclear issue and the South Korea-U.S. alliance.

Campbell’s Seoul visit comes on the heels of his trip to Japan and just before his stop in Thailand where he’ll participate in next week’s ASEAN Regional Forum.