The White House threatened sanctions on buyers of Iranian oil in an effort to intensify a naval blockade on the Strait of Hormuz.

The move is in practice targeted at China, which before the war bought more than 80% of Iran’s crude exports. US Treasury Secretary Scott Bessent said he believed China would pause such purchases under the threat of secondary sanctions.

The move imperils the fragile trade truce between the two superpowers ahead of US President Donald Trump’s planned visit to China next month, when he hopes to unveil a trade deal. Further imperiling ties are reports that Beijing is backing Tehran with a spy satellite and weapons systems.