US President Joe Biden held talks online Friday with his counterparts from Australia, India and Japan, taking consultations in the four-country group known as the Quad to the highest level. The virtual summit of the leaders, who plan to meet in person later this year, was described by Jake Sullivan, US national security adviser, as “a big deal” for Biden and the US.

The top-level meeting of the Quad countries demonstrated the will of the Biden administration to work together closely with US allies and partners in the Indo-Pacific region to counter a rising China.

An outline of its foreign policy released early this month said the US would “rally our allies and partners to join us, pooling our negotiating leverage and showing our collective power and resolve.” The Interim National Security Guidance noted that China’s leaders too often “behave aggressively and coercively” and pledged that the US would “position ourselves, diplomatically and militarily, to defend our allies.”

In his speech made to coincide with the release of the guidance, US Secretary of State Antony Blinken said that the US was ready to confront China wherever necessary, describing Washington’s relationship with Beijing as the “biggest geopolitical test” of the century. He stressed the US will engage China from a position of strength.

Friday’s Quad summit is to be followed by a trip to Seoul and Tokyo by Blinken and US Defense Secretary Llyod Austin this week. During the tour, they will meet their counterparts from South Korea and Japan to discuss cooperation with Washington’s two key Asian allies.

Against this backdrop of its closer coordination with allies and partners in the region, the US will hold the first high-level meeting with China later this week since Biden took office in January. Blinken and Sullivan will meet Yang Jiechi, China’s top foreign policy official, and Wang Yi, its foreign minister, in Alaska on Thursday in an engagement that is expected to set the tone of relations between the two superpowers during the Biden presidency.

Amid the steadfast steps being taken by the US to build up a web of allies and partners against China, President Moon Jae-in’s administration in Seoul is finding it increasingly difficult to maintain an ambiguous stance between Washington and Beijing.

Washington is expected to gradually lengthen the to-do list for Seoul as its key ally -- from enhancing trilateral cooperation with Tokyo to joining its push to expand the Quad group and cooperating for its plan to deploy advanced missiles aimed at China in the western Pacific region. The forthcoming visit to Seoul by Blinken and Austin, which follows their two-day stay in Tokyo from Tuesday, might signal that South Korea’s prolonged hesitance to be aligned with Washington’s principled approach to Beijing could run the risk of erasing its room for diplomatic maneuvering instead of enabling it to remain in the gray zone.

The Moon government has recently expressed its wiliness to improve frayed ties with Japan, though it seems more cautious on whether to allow the US to deploy advanced missiles targeting China here.

It remains ambiguous on the issue of South Korea joining a possible expanded format of the Quad, having sent confusing signals. In an article published in a US magazine last week, a member of South Korea’s presidential policy planning commission said the Moon government was considering joining an envisioned Quad plus to show its commitment to the South Korea-US alliance and, indirectly, influence Biden’s North Korea policy. But First Vice Foreign Minister Choi Jong-kun later struck a negative tone on Seoul’s participation, saying in a radio interview that South Korea has been consistently against the establishment of a regional structure excluding or checking a certain country.

If anything, it would prove wiser for Seoul not to be late in making clear its willingness to join an expanded Quad.

The current Quad countries now focus on a broad strategy of finding common fields where they counter Beijing without forming an overtly anti-China front. South Korea needs to join early-stage discussions within the emerging multilateral framework if it wants to inject a more inclusive view while standing alongside other participants on key democratic values.

Eventually, it will not be able to afford to stay out of the scheme the Biden administration is seeking to use as a vital tool to forge a global solidarity against China in both security and economic terms. A belated move to join the Quad would only amplify China’s ire and receive a half-hearted welcome from the US.