WASHINGTON, Feb. 8 (Xinhua) -- U.S. State Department said Friday that Stephen Biegun, U.S. special representative for the Democratic People's Republic of Korea (DPRK), concluded his three-day visit to the DPRK.

In Pyongyang, Biegun and his DPRK counterpart Kim Hyok Chol discussed advancing the commitments that U.S. President Donald Trump and the DPRK's top leader Kim Jong Un made in their Singapore summit last June, according to a statement issued by the State Department.

Trump announced on Friday that his second meeting with Kim Jong Un would take place in Hanoi, Vietnam on Feb. 27-28 and he also said that Biegun had "a very productive" meeting in the DPRK.

The statement said that Biegun and Kim Hyok Chol agreed to meet again in advance of the second Trump-Kim summit.

In his speech at Stanford University in California on Jan. 31, Biegun said he expected to achieve "a set of concrete deliverables" through working-level negotiations with Pyongyang ahead of the scheduled leaders' summit, while reiterating that sanctions against the DPRK would not be removed until denuclearization is complete.

The U.S.-DPRK relations improved last year. However, differences between the two sides remain over critical issues including the scale of denuclearization, U.S. sanctions and whether to issue a war-ending declaration.