TEHRAN, Aug. 24 -- Every tanker captain navigating the Strait of Hormuz now carries two sets of obligations that cannot both be satisfied. One comes from Washington. The other, announced Monday, comes from Tehran.

Iran's Persian Gulf Strait Authority warned that vessels violating the Islamic Republic's transit protocols for the Strait of Hormuz will be added to a Non-Compliant Vessels list, and that any ship on that list faces fines, seizure, or confiscation on future transits, Sputnik reported Monday. Cargo owners were specifically urged to check the list before chartering ships. Any vessel conducting ship-to-ship transfers with a blacklisted carrier would itself be added.

The announcement converts what has long been a diplomatic dispu...