Lesotho, May 20 -- When President Donald Trump arrived in Beijing for his much-publicised summit with Xi Jinping, the world expected spectacle. It received it in abundance. Grand halls, military ceremony, carefully choreographed diplomacy and declarations of "stable relations" dominated the headlines. Yet behind the visual theatre lay a more consequential geopolitical reality: America travelled to China not from a position of uncontested dominance, but from a position of strategic necessity.

The central issue shadowing the visit was not trade alone, nor tariffs, nor Taiwan. It was the growing instability surrounding the Iran war and the global economic danger created by disruptions in the Strait of Hormuz. Nearly a fifth of globally traded...