The Trump administration's tariff war with China is most often seen through the lens of the economy. But to many economists, the bigger threat is that Trump's global trade gambit will erode the United States’ main source of global authority: the long-term geopolitical relationships it has cultivated over nearly a century.

Japan and South Korea have rebuffed Beijing’s suggestion that they form a united front against Trump as the U.S. allies try to negotiate lower tariffs.