The recent threat by Iran to “bar foreign warships from the Gulf” raises a classic issue in the law of the sea – the legality of coastal states demanding authorization for warships to pass through their waters. The water in question is the Strait of Hormuz, linking the Persian Gulf with the Gulf of Oman and the Arabian Sea. It is an incredibly important route for international shipping and “one of the world’s most strategically important choke points.” Apparently, the Iranian regime has warned the US navy that its vessels are not welcome in the Persian Gulf and the proposed legislation before the Iranian legislature is intended to provide a basis for preventing the passage of foreign warships.