OSAN AIR BASE, South Korea — US President Joe Biden arrived in South Korea Friday, his first Asia trip as US leader, aiming to cement ties with regional security allies as concern over a North Korean nuclear test grows.
Biden wants the trip to build on recent moves accelerating a years-long US pivot to Asia, where rising Chinese commercial and military power is undercutting Washington's dominance.
He will receive a warm welcome from South Korea's new staunchly pro-US President Yoon Suk-yeol, who took office last week, but there is growing concern North Korea's unpredictable leadership could conduct a nuclear test during Biden's visit to the region.
Despite a spiraling COVID outbreak, Pyongyang's "preparations for a nuclear test have been completed and they are only looking for the right time," South Korean lawmaker Ha Tae-keung said after being briefed by Seoul's spy agency.
US National Security Advisor Jake Sullivan said there was "real risk of some kind of provocation while we're in the region".
"We know what we will do to respond to them. We have communicated with not just our allies, but also with China," he said.
Hawkish Yoon has pledged to take a firm line with the North after years of failed diplomacy, and also wants stronger ties with the US, including ramping up joint military exercises.
Early Friday, he told reporters in Seoul that Biden's trip was an opportunity for the US-South Korea relationship to become "stronger and more inclusive".
Biden heads to Japan from South Korea on Sunday. He will hold talks with the leaders of both countries, as well as joining a regional summit of the Quad -- a grouping of Australia, India, Japan and the United States -- while in Tokyo.
"I’m on my way to the Republic of Korea and Japan for my first trip to Asia as president," Biden tweeted from Air Force One.
"I look forward to strengthening vital security alliances, deepening our economic partnerships, and working with fellow democracies to help shape the rules of the road for the 21st century."
The fact that Biden is visiting Seoul first indicates that Washington is looking to re-focus on the Korean Peninsula, Soo Kim, a former CIA analyst now with the RAND Corporation, told AFP.
Both Seoul and Washington may be looking to "bridge the policy gap" and plan how the security allies could better coordinate "in the face of current and emerging challenges in the region and beyond," Soo Kim said.
If Kim does test a nuclear weapon during the visit, the US said its response would be coordinated with South Korea and Japan -- and could include "adjustments to the way that our military is postured in the region," Sullivan said.
The US has nearly 30,000 troops in South Korea -- some of whom Biden will visit on the trip -- and about 55,000 US military personnel in Japan.
The unintended effect of a nuclear test during the visit could be to draw Washington and Seoul ever closer, Soo Kim said.
"Should Kim proceed with a test during Biden’s visit, he will effectively be helping the two countries find greater justification to work together on the North Korea issue," she added.
Sullivan also said that a North Korean nuclear test would not be seen as a setback for Biden's diplomacy.
"It would underscore one of the main messages that we are sending on this trip, which is that the United States is here for our allies and partners."
Sullivan said ahead of the trip that Biden is bound for Asia with "the wind at our back" after successful US leadership in the Western response to President Vladimir Putin's now almost three-month-long invasion of Ukraine.
The high military, diplomatic and economic cost imposed on Russia is seen in Washington as a cautionary tale for China, given Beijing's stated ambitions to gain control over democratic-ruled Taiwan, even if that means going to war.
Sullivan said the administration wants not so much to confront China on the trip as to use Biden's diplomacy to show that the West and its Asian partners will not be divided and weakened.
He pointed to cooperation from South Korea and Japan, among others, in the sanctions regime against Russia led by European powers and the United States. He also referred to Britain's role in the recently created security partnership AUKUS.
This "powerful message" will be "heard in Beijing," Sullivan said, "but it's not a negative message and it's not targeted at any one country."
© Agence France-Presse