The global trading system has underpinned huge growth in trade and the integration of economies that have signed on to it, whether they are political allies or not—none more so than in the Asia-Pacific region. It has prevented political disputes between Japan and China adversely affecting trade and investment flows between the two countries. The World Trade Organisation continues to play an important role. This is evidenced by the number of countries still willing to join the organisation, its record in keeping markets open during crises and the effectiveness of the dispute settlement mechanism. Yet the global trading system faces challenges. The rules and agenda, as well as the single undertaking mode of negotiations, are not effective or relevant to commerce in the twenty-first century. The shift to mega-regional agreements further undermines its primacy. A weakened global trading system could also have negative spillovers for political relations between countries.