China buys 80% of Iran's oil exports. Treasury sanctioned a tanker and a Hong Kong shipper — not the banks tied to the U.S. financial system.

Exerting maximum economic pressure on Tehran would risk blowback from Beijing.

Washington has intensified its efforts to clamp down on Chinese purchases of Iranian oil since Trump returned to the White House last year.

The United States is unveiling new sanctions against Iran today. These measures aim to cripple Iran's economy by targeting its oil sales. China buys most of Iran's oil and…