China is drawing a line in the sand over Iranian oil. Beijing has warned the US that it will retaliate if the Trump administration follows through on expanding secondary sanctions that hit Chinese companies involved in Iran’s petroleum trade.

The warning comes after the US Treasury announced broader sanctions on August 24, 2026, under the dramatically named “Operation Economic Outcast.” The action targets 60 entities, individuals, and vessels, and threatens secondary sanctions against any country or firm that maintains economic ties with Tehran.

The oil pipeline Washington can’t shut off

China buys roughly 80% of Iran’s crude oil shipments. Beijing has made clear it has no intention of cutting the cord.

Chinese officials have vowed to protect the country’s “legitimate rights and interests” in the face of US pressure. More than just rhetoric, Beijing has taken a concrete step that signals real escalation: invoking its “blocking rule” for the first time to defy US sanctions on Iranian oil.