Washington, Feb 21 (IANS): 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 second summit with North Korean leader Kim Jong-un in Vietnam.

Bolton's trip comes as top US officials continue to hammer out the details of the US President's second summit with Kim, CNN reported on Wednesday. The two first met in June last year in Singapore where they agreed to work towards denuclearization of the Korean Peninsula in exchange for security guarantees for the Kim regime.

But no real progress was made. Now, the February 27-28 Hanoi summit is expected to help the stagnating talks move forward.

US 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 Singapore summit and was at the table for Trump's discussions with Kim and other North Korean officials.

The NSA has long been a sceptic of a diplomatic resolution to North Korea's nuclear threat and made clear that Kim was yet to take concrete steps towards denuclearization.

In December, he said the second summit was necessary because Kim had not lived up to commitments he made during the first summit.

"They have not lived up to the commitments so far," Bolton told The Wall Street Journal's annual CEO Council conference in Washington. "That's why I think the President thinks that another summit is likely to be productive."