The United States has warned shipping companies that they could face sanctions if they pay tolls to Iran to pass through the Strait of Hormuz. Iran claims it has begun collecting toll revenue, though it has not disclosed how much has been gathered or from whom. The Office of Foreign Assets Control said payments could include cash, digital assets, charitable donations, or other indirect methods, and warned that even non-United States entities could face civil or criminal penalties if such payments involve United States financial systems.

Tensions have escalated since fighting began in February, with Iran targeting vessels in the strait and seizing two ships. In response, the United States imposed a naval blockade on Iranian ports in April, turning away dozens of commercial vessels. Iran has described the interceptions as piracy.

The United States Treasury has also imposed new sanctions on three Iranian currency exchange houses, accusing them of converting oil revenue into usable foreign currencies. Officials said they will continue targeting Iran's key revenue sources, particularly its petroleum and petrochemical sectors. Ship traffic through the strategically vital waterway, which is essential for global oil and goods shipments, has dropped sharply from around three thousand vessels a month to only a few each day.