Jakarta, March 20 -- The global trading system, a pillar of shared prosperity, is now under siege. The specter of trade protectionism, roused by Washington's sweeping tariffs on major trading partners, threatens to unravel decades of economic progress.

For ASEAN, a region whose growth has been fueled by open markets, this is not a distant storm but an imminent crisis. Now, more than ever, Southeast Asia and China must forge a united front against these destabilizing forces and champion free trade as the cornerstone of their shared economic future.

The ASEAN-China economic partnership has long been a model of mutual benefit. Since 2009, China has stood as ASEAN's largest trading partner, while ASEAN dethroned the EU as China's top tradin...