This Jan. 28, 2019 photo shows U.S. National Security Advisor John Bolton takes questions from reporters at the White House in Washington, D.C. UPI-Yonhap

U.S. National Security Adviser John Bolton is in Hanoi for President Donald Trump's second summit with North Korean leader Kim Jong-un, his spokesman said Tuesday.

There had been speculation that the hawkish adviser had been left out of Trump's delegation, because his name was not on a list of officials distributed by the White House.

Bolton's spokesman, Garrett Marquis, confirmed in an email that Bolton was already in the Vietnamese capital ahead of the president's scheduled 9:15 p.m. arrival.

Official: Trump- Kim summit schedule 2019-02-26 10:39  |  North Korea
Asked if he will be participating in all of Trump's meetings with Kim, a White House spokesperson replied, "The attendance has not yet been announced by the White House."

Bolton is known for his hardline stance on North Korea. He has repeatedly expressed skepticism over whether the regime will abandon its nuclear weapons program. But in recent months he has softened his public remarks in apparent consideration of Trump's eagerness to engage with Kim.

The adviser had been scheduled to visit South Korea last week for talks with his South Korean and Japanese counterparts on the summit but later canceled the trip to focus on events in Venezuela. (Yonhap)