Washington (CNN) US National Security Advisor John Bolton will travel to South Korea later this week for a round of consultations ahead of President Donald Trump's upcoming summit with North Korean leader Kim Jong Un, two administration officials told CNN.

Bolton's trip comes as top US officials continue to hammer out the details of Trump's second summit with Kim. From the pageantry of the meeting to the substance of what Trump and Kim might agree to regarding denuclearization there's much to be worked out.

South Korea is a crucial partner in US diplomacy with North Korea and South Korean President Moon Jae-in has been the biggest proponent of Trump's continued engagement with Kim.

Secretary of State Mike Pompeo has been the diplomatic lead on the North Korea negotiations in Trump's Cabinet, even though Bolton has remained closely involved in policy discussions on North Korea. Bolton attended the last Trump-Kim summit in Singapore and was at the table for Trump's discussions with Kim and other North Korean officials.

When asked about the trip, National Security Council spokesman Garrett Marquis said the NSC had "nothing to announce right now."

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