By David Brunnstrom and Michael Martina
WASHINGTON (Reuters) - A U.S. summit with Japan and South Korea on Friday will include an ambitious set of initiatives to lock in progress between the allies, White House Indo-Pacific coordinator Kurt Campbell said on Wednesday.
Campbell said the U.S. relationship with Japan and South Korea would be a "defining trilateral relationship for the 21st century."
Senior U.S. administration officials have told Reuters the summit will launch joint initiatives on technology and defense, amid mounting shared concerns about China and North Korea.
"What you will see on Friday is a very ambitious set of initiatives that seek to lock in trilateral engagement, both now and in the future," Campbell told a Brookings Institution event.
The summit, at the Maryland presidential retreat of Camp David will be the first standalone meeting between the U.S. and its two allies. Campbell said plans would be announced to make it an annual event and also to invest in technology for a three-way crisis hotline.
U.S. President Joe Biden invited Japanese Prime Minister Fumio Kishida and South Korean President Yoon Suk Yeol to Camp David as the Asian nations work to mend their tattered diplomatic relations in the face of rising regional threats.
Washington has formal collective defense arrangements in place with both Tokyo and Seoul separately, but it wants them to work closer together given growing concerns about China's mounting power and intentions.
However, U.S. officials said the meeting will stop short of any formal three-way security framework and Campbell acknowledged domestic political constraints in the countries.
He said agreements reached at the summit would be "a substantial step forward in recognizing the common security picture that each of the countries are facing" and recognizing that "it will require common actions."
"I think we can imagine a future with more ambition, but ... the key is not to get too far over your skis, to take this a step at a time to build appropriately to not get beyond the domestic context of which we're dealing."
Campbell said the three would explore how to extend their security cooperation but do so "prudently," "carefully" and "responsibly."
He praised the courage of Yoon and Kishida in mending ties fraught with historical baggage, stemming particularly from Japan's past colonial rule of Korea, calling it "a breathtaking kind of diplomacy."
"It belongs on the top tier with respect to diplomatic initiatives of modern times," he said.
Campbell said the aim of the summit was to "try to embed this in our politics in such a way that it will be hard for any leader in either of the three countries" to back out of.
His comment alluded both to the perceived fragility of the Seoul-Tokyo rapprochement and to concerns about the stance of a future U.S. government after former President Donald Trump voiced skepticism about whether Washington benefits from its traditional alliances.