While Trump announced his navy would block “all ships” in Hormuz, two Chinese state-owned supertankers crossed the strait untouched. They sailed near the Iranian coast, passed through and emerged into open waters. The US Navy, with its entire armada deployed, watched them go.

Fortune asked it openly: “It’s unclear if the US would forcibly stop a Chinese tanker.” A retired Canadian admiral put it bluntly: boarding China-linked ships would be “pretty dicey.” A CBC analyst warned it “borders on an act of war” under international law.

The China-Iran relationship is no small detail. China buys 80% of Iran’s oil and pays in yuan, not dollars. The tolls Iran charges ships in Hormuz are also paid in yuan. They’re building a parallel financial system that doesn’t need Washington.