WASHINGTON/SEOUL -- A senior US diplomat will visit South Korea next week for further coordination ahead of both countries' summits with North Korean leader Kim Jong-un.

Susan Thornton, acting assistant secretary of state for East Asian and Pacific Affairs, will travel to Seoul Sunday to Tuesday and then Tokyo Tuesday to Friday, the State Department said in a press release.

"During her visits to our treaty allies in Northeast Asia she will reaffirm US alliance commitments and coordinate on issues of importance for the maintenance of security and prosperity in the region," the release said. "She will also discuss cooperation in the Indo-Pacific region and the continued close coordination on (North Korea)."

Thornton will meet with South Korean officials, including Foreign Minister Kang Kyung-wha and deputy foreign minister Yoon Soon-gu, to have in-depth discussions on ways to denuclearize the North, establish peace on the peninsula and step up their alliance and coordination on those issues, according to Seoul's foreign ministry.

The allies are preparing for high-stakes talks between South Korean President Moon Jae-in and Kim on April 27, and between US President Donald Trump and Kim in May or June.

Moon and Trump will be going into the meetings seeking to begin a process to rid the North of its nuclear weapons. (Yonhap)