File Photo: U.S. Secretary of State Mike Pompeo (R) meets with South Korean Foreign Minister Kang Kyung-wha at the U.S. Department of State in Washington D.C., the United States, on Dec. 6, 2018. (Xinhua/Ting Shen)

WASHINGTON, Feb. 15 (Xinhua) -- U.S. State Department said Thursday that U.S. State Secretary Mike Pompeo has held talks with South Korean Foreign Minister Kang Kyung-wha in Warsaw to discuss their ongoing efforts to achieve denuclearization of the Korean Peninsula.

During a meeting on the sidelines of the Middle East security conference in Warsaw, Pompeo and Kang discussed the denuclearization of the Korean Peninsula, updated each other's engagements with Pyongyang, reaffirmed the alliance of the two countries, and expressed their commitment to the U.S.-South Korea-Japan trilateral cooperation, according to the State Department.

In an interview with the CBS News the same day, Pompeo revealed that the United States would send a work team to Asia this weekend to prepare for the upcoming summit between U.S. President Donald Trump and top leader of the Democratic People's Republic of Korea (DPRK) Kim Jong Un in Vietnam's capital Hanoi at the end of February.

"Now it's time for us to begin the effort to take the step on denuclearization, and I'm hopeful that this summit will deliver that," Pompeo said.

Stephen Biegun, U.S. special representative for DPRK affairs, last week had a three-day visit to Pyongyang, where he and his DPRK counterpart Kim Hyok Chol had a discussion on advancing the commitments that Trump and Kim Jong Un made in their Singapore summit last June.

On Jan. 31, Biegun said that the U.S. side expects to hold working-level negotiations with DPRK in advance of the summit with the intention of achieving a set of concrete deliverables, reiterating that sanctions against the DPRK would not be removed until denuclearization is complete.

According to the U.S. State Department, Biegun and Kim Hyok Chol agreed to meet again before the second Trump-Kim summit.

South Korean President Moon Jae-in said Monday that the second DPRK-U.S. summit would go a step forward to be a critical turning point that would more concretely and visibly advance the peninsula's complete denuclearization, new DPRK-U.S. relations, and a peace regime on the peninsula, which were agreed to at the first DPRK-U.S. summit in principle.

A Vietnamese delegation led by Deputy Prime Minister and Foreign Minister Pham Binh Minh traveled to Pyongyang on Tuesday for a three-day visit at the invitation of DPRK Foreign Minister Ri Yong Ho. The meeting was believed to focus on the upcoming summit between Kim and Trump.

Trump announced on Feb. 8 that his second meeting with Kim would take place in Hanoi on Feb. 27-28. He met with Kim for the first time in Singapore on June 12, 2018, reaching several consensuses, at least in principle, and that have led to the improvement of the U.S.-DPRK relations.

However, differences between the two sides on such key issues as the roadmap of denuclearization, U.S. lifting sanctions and whether to issue a war-ending declaration, still haunt the two sides and hinder negotiations.