An upcoming visit to Seoul by top US diplomatic and defense officials may serve as an occasion to send a signal that South Korea can no longer sustain its ambiguous position between the US and China.

US Secretary of State Antony Blinken and Defense Secretary Llyod Austin are expected to make a two-day visit to Seoul starting March 17 following their three-day stay in Tokyo, according to diplomatic sources here and a report by a Japanese news agency last week.

Their choice of Washington’s two key Asian allies for their first overseas trip since taking office in late January shows the will of US President Joe Biden’s administration to keep a rising China in check in cooperation with allies and partners.

An outline of the Biden administration’s foreign policy released Wednesday 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, 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.

“Our relationship with China will be competitive when it should be, collaborative when it can be and adversarial when it must be,” he said, stressing the US will engage China from a position of strength.

Blinken and Austin’s planned talks with their Japanese counterparts are set to demonstrate the strengthened alliance between the US and Japan. In time for their visit, leaders of the Quad group, which involves Australia and India as well as the US and Japan, are expected to hold their first summit in the form of on-line gathering. Tokyo is playing a key role in consolidating the quadrilateral framework, which the Biden administration is seeking to use as a key tool to forge a global solidarity against China.

During their visit to Seoul, the top US officials are likely to face a reserved response from South Korean officials to their call for joint steps toward China. Washington is expected to gradually lengthen the to-do list for Seoul as its key ally -- from enhancing trilateral collaboration with Tokyo to joining its push to expand the Quad and cooperating for its plan to deploy advanced missiles aimed at China in the western Pacific region.

President Moon Jae-in’s administration now needs to recognize a prolonged hesitance to be aligned with Washington’s principled approach to Beijing could run the risk of erasing Seoul’s room for diplomatic maneuvering instead of enabling it to remain in the gray zone.

Biden’s predecessor Donald Trump took aggressive measures against China in a unilateral manner, while putting US economic interests ahead of alliances based on shared values. But the Biden administration is seeking to build back alliances from more balanced viewpoints to join forces to counter an increasingly assertive China, which Blinken described in his recent speech as the only power to seriously challenge the stable and open international system.

South Korea cannot position itself equally distanced from the US and China as the competition between the two superpowers escalates to a new dimension. The country may have much to lose from being estranged from China, its largest trading partner. But economic interests with China cannot be on par with the importance of its crucial security alliance with the US based on shared values.

The Moon administration seems concerned about the consequences of tensions between the US and China for its blind pursuit of inter-Korean reconciliation. This attitude will stand in the way of strengthening Seoul’s joint security posture with Washington.

Seoul needs to be quick to enhance trilateral cooperation with the US and Japan and respond to Washington’s bid to expand the Quad, though it might have to be more cautious on whether to allow the US to deploy missiles targeting China on its soil. Based on this stance, Seoul might find a role in facilitating cooperation between the two superpowers in areas where it could be possible.

South Korea should not be perceived by China as the weakest link in the network of allies and partners with the US. A persistently firm alliance with Washington would eventually lead Beijing to try to placate Seoul.