The past year of U.S.-Chinese relations has been extraordinary and head-spinning. In the spring of 2025, U.S. President Donald Trump imposed a de facto trade embargo on China, a measure swiftly reciprocated by Beijing. Months later, he was touting a “G-2” partnership between the two countries. In recent weeks, Trump has both invited Chinese warships to the Strait of Hormuz and threatened to strike China-bound oil tankers passing through it. But the world’s most important bilateral relationship has also changed in more consequential and persistent ways. China has quietly established authority over whether and how the United States will implement national security measures such as export controls. Stylistic changes in how the United States conducts diplomacy with China have allowed Beijing to gain the upper hand in pushing for high-stakes policy concessions.…