Richard Maude is executive director of policy at Asia Society Australia.

The Association of Southeast Asian Nations begins three days of intense regional summitry today, facing a barrage of tests to its relevance, internal cohesion and social and economic health.

Chaired by Brunei, Southeast Asian leaders will meet virtually for their end-of-year summit and a suite of meetings that have ASEAN at their core. Most important of these is the annual leaders' meeting of the 18-member East Asia Summit, which includes the U.S., Russia and China.

ASEAN has notched up significant achievements in recent decades -- helping keep peace in the region, steadily building a globally connected economic community and cementing its place at the heart of Indo-Pacific economic and security cooperation architecture. But 2021 has seen a perfect storm of internal and external challenges.

Having kept COVID-19 mostly at bay during 2020, the rapid spread of the delta variant has resulted in thousands of deaths and plunged many more into poverty, slowing the region's uneven economic recovery. Efforts to deal with the crisis in Myanmar have foundered, and geopolitics are catching up with ASEAN as Washington intensifies efforts to balance China's power.

For years, ASEAN has carefully nurtured the idea of its "centrality" to economic, political and security cooperation and dialogue in the broader Indo-Pacific. In doing so, it has hoped to influence the actions of the major powers while preserving some degree of agency in a more contested era. But ASEAN centrality is a chimera when it comes to the now white-hot contest for power and influence.

The new trilateral partnership involving the U.S., the U.K. and Australia known as AUKUS is a sharp and -- for some, especially Indonesia and Malaysia -- unwelcome reminder of the new era.

Still reverberating through the region, ASEAN understands that AUKUS is one part of a much larger dynamic, with the Quad -- an informal partnership of the United States, Japan, India and Australia -- increasingly positioned as a bulwark against Chinese military aggression. Quad countries seek to balance China and build a multipolar regional order safe for democracies.

ASEAN's anxieties are threefold: of being caught up in a future conflict, of being forced to "pick a side" and of losing its relevance amid the most pressing challenge of the age. Still, ASEAN was not built to manage major-power competition, and it is unreasonable to expect it to do so.

Instead, the task for ASEAN is to find a productive coexistence with the Quad and new partnerships such as AUKUS. This is both possible and necessary. The Quad is here to stay, but its members all recognize the importance of a strong ASEAN and the value of its inclusive regional architecture.

For its part, ASEAN must accept the right of the Quad countries to make their own choices about China's rise -- to protect their sovereignty and respond to genuine concerns about Beijing's coercive diplomacy and zero-sum regional ambitions.

Some in Southeast Asia are quietly supportive of efforts to sustain a military balance in the region. Others instinctively point the finger of blame at everyone but China for disturbing the peace, underlining how conditioned ASEAN has become at avoiding even the mildest public criticism of Beijing.

While Malaysia and Indonesia have expressed concerns about Australia's nuclear submarine project, neither country apparently feels the need for ASEAN to have a similar discussion about China's massive military modernization and the insecurity this is breeding. This is not what "not picking sides" looks like.

The Quad is here to stay, but its members all recognize the importance of a strong ASEAN and the value of its inclusive regional architecture.   © AP

Southeast Asia does have every right to call, as Singaporean Foreign Minister Vivian Balakrishnan did recently, for the U.S. and China to manage their competition responsibly and for external powers to engage the region "on our merits, rather than be seen purely through the lens of the U.S.-China competition."

The Quad is in part answering this call, with its strong emphasis on contributing to regional public goods, especially in fighting the pandemic and supplying vaccines, in addition to major contributions to ongoing ASEAN projects involving infrastructure, smart cities and management of the Mekong.

Still, it is bilateral diplomacy that will carry the most weight in convincing Southeast Asian countries they are valued in their own right. Here, US diplomacy needs a course-correction.

The Biden administration deserves credit for starting the flow of U.S.-made vaccines, and its regional narrative emphasizing shared principles like peaceful settlement of disputes generally works well.

But while Singapore, Vietnam and the Philippines -- all countries important to Washington's Indo-Pacific strategy -- have hosted high-profile visits from Vice President Kamala Harris and Secretary of Defense Lloyd Austin, Indonesia worries that it is a second-order priority.

A challenging domestic agenda and the global distractions of a superpower mean the Biden Administration cannot be everywhere.

But Indonesia is the linchpin of ASEAN, a Group of 20 member, and a trillion-dollar economy with the fourth largest population in the world. The United States has enormous direct bilateral interests tied up in Indonesia's future prosperity and stability.

And, as it happens, a resilient, democratic and successful Indonesia is also the best hedge against a future Southeast Asia dominated by China. Washington should pay it more attention.