The two senior US officials arrived in Hanoi with a delegation to get ready for the second, two-day summit between U.S. President Donald Trump and North Korean leader Kim Jong-un that opens Wednesday.

Nearly 250 U.S. officials are set to arrive in Hanoi today, and President Trump is expected to land in Hanoi tonight.

The delegation of U.S. Secretary of State Mike Pompel and National Security Advisor John Bolton arrive in Hanoi on Tuesday morning. Photo by VnExpress/Gia Chinh

The U.S. Department of State had said earlier that Pompeo will be in Hanoi Tuesday to Thursday to attend the summit before meeting with Vietnamese officials.

He will then go to the Philippines to meet President Rodrigo Duterte and his counterpart Teodoro Locsin, Jr. on Thursday.

Trump’s adviser Bolton is known to have hawkish opinions on North Korea denuclearization. He told U.S. media that the U.S. has lived up to the Singapore declaration that followed the June 12 summit.

"It’s just North Korea that has not taken the steps we feel are necessary to denuclearize," Bolton said, adding that the relaxation of any sanctions was not under consideration.

In an interview with Fox Business Network last week, Pompeo said President Trump was "not ratcheting down expectations" about what could be achieved at the second summit with North Korean leader Kim Jong-un.

He said progress has been made in negotiations and denuclearization is a feasible outcome.