Top South Korean negotiators have traveled to the United States on Thursday to brief American National Security Adviser Lt. Gen. H.R. McMaster on their recent visit to North Korea.

Top South Korean negotiators have traveled to the United States to brief American National Security Adviser Lt. Gen. H.R. McMaster on their recent landmark visit to North Korea and Pyongyang’s conditional offer to negotiate over its weapons programs.

South Korean officials have had a historic meeting with North Korean leader Kim Jong Un earlier this week.

Head of National Security Office Chung Eui-yong and National Intelligence Service chief Suh Hoon, who paid a two-day historic visit to the North earlier this week, left Incheon International Airport, west of the capital, Seoul, for Washington.

A South Korean government official, speaking on condition of anonymity, said that the pair would also speak with other US department heads and later possibly meet either American President Donald Trump or Vice President Mike Pence.

The source added that Chung had already spoken to McMaster on the phone shortly after completing his visit to Pyongyang.

On Tuesday, Chung said that North Korean leader Kim Jong-un had expressed willingness to abandon nuclear weapons “if military threats toward the North are cleared and the security of its regime is guaranteed.”

The South Korean officials are expected to discuss that offer with the US officials.

Washington has long included itself in the Korean dispute. It has heavy military presence in the region and uses North Korea’s ballistic and nuclear programs as a pretext to constantly threaten Pyongyang with military action.

That military posture has concerned the North, which says it needs to advance its weapons program to protect itself against potential US military action.