President Moon Jae-in was unexpectedly quick to accept an invitation from US President Donald Trump to a Group of Seven summit slated for this fall.

During their phone conversation Monday, the second in about six weeks, Moon expressed gratitude for the invitation, reaffirming Seoul’s commitment to play a global role in quarantine and economic fields.

Trump earlier told reporters that he would like to invite South Korea, Australia, India and Russia to this year’s G-7 summit the US is planning to host in time for the convening of the UN General Assembly in September.

The US has made no secret of its intention to use an expanded G-7 meeting as a possible tool to add pressure on China, with which it is engaging in an escalating confrontation over a widening range of issues.

Caught in the mounting rivalry between the US, its traditional ally, and China, its biggest trading partner, South Korea was expected to dither over whether to accept Trump’s offer.

It would have been just insensible, if the country had rejected the chance of becoming a member of a key international dialogue framework larger than the G-7 but smaller than the G-20.

Though Trump might seek to use the expanded G-7 summit as a stage to show solidarity against China, it could also serve to shape up global cooperation in preparing for the post-coronavirus pandemic era. The current G-7 system seems increasingly outdated and limited in responding to global challenges and finding solutions.

Participating in the envisioned G-11 summit, which might be joined by Brazil, would enable South Korea to play a role commensurate to its status as the world’s 10th-largest economy. Joining it would not be incompatible with maintaining cooperative ties with China.

Moon’s quick acceptance of Trump’s invitation comes at a time when his government is pushing for Chinese President Xi Jin-ping’s visit to Seoul within this year.

These moves could be seen as signaling Seoul is trying to go beyond what it has described as strategic ambiguousness between the two superpowers to secure space for its own diplomatic maneuvers.

It seems to hope that its diplomatic outreach will be bolstered by the country’s enhanced image built up through its relatively successful handling of the COVID-19 outbreak.

But experts say such an effort may end up with a failed attempt to strike a balance between the two superpowers as Washington and Beijing will try harder to draw Seoul into its fold.

Apparently, the goal for the Moon government is not to tilt toward either of the two superpowers. This is likely to be a nearly impossible position for South Korea to keep in the budding Cold War between the US and China, which might unfold for decades to come.

A day after Trump’s offer, US Secretary of State Mike Pompeo, who has been at the forefront of Washington’s campaign against China, singled out South Korea among the countries Washington expects to be on board with its stance.

Alliance with the US is certainly more essential to South Korea’s vital interests than strategic cooperative partnership with China.

The problem is Seoul has too much to lose by getting estranged from China, which accounts for 24 percent of its external trade, compared with 9 percent with the US and 7 percent with Japan.

But it may not be possible to sit on the fence forever.

In the worst-case scenario, South Korea could be shunned not only by Beijing but also by Washington. Being shut out of the Economic Prosperity Network pushed by the US as a counterweight to China’s economic power could do more damage to South Korea than a backlash from Beijing would.

Under these circumstances, the country needs to commit to the alliance with the US and reduce its overreliance on China in the economic field.

Based on this approach, Seoul might seek to play a role in helping promote cooperation between the US and China, which is critical to solving global problems and the North Korean nuclear issue. If an expanded G-7 summit takes place as envisioned by Trump, South Korea may act as a buffer when discussions become too exclusive of China.

Restoring and strengthening cooperative ties with Japan will be needed for South Korea to make such an endeavor more effectively.

To avoid weakening the alliance with the US amid the delicate situation, the Moon administration also needs to pay heed to US calls for inter-Korean projects to be in step with progress in denuclearizing the North.