Open the Strait, and keep it wide & open

On Sunday, Trump said the US Navy would 'immediately' start blockading the Strait of Hormuz and would also intercept every vessel in the international waters that had paid a toll to Iran for passage. The move to charge transit fees for merchant vessels crossing the strait - first imposed by Tehran and now threatened by Washington - on the strait sets the clock back on maritime convention by decades. Littoral nations are not allowed to charge for use of international waterways, except for pilot and port services. Iran has been ambivalent about the UN Convention on the Law of the Sea but has abided by it so far. Its claim for a Hormuz transit fee was its first significant departure from international convention, as will be the US' if it comes into effect as the result of further escalation. In either case, international shipping through the Hormuz Strait would not be free, an earlier US criterion for ceasefire.

There is no precedent in modern maritime history to such a blockade, and a solution will have to be drawn up from scratch. Russia and China have vetoed a UNSC resolution to reopen the Hormuz Strait. Military action to force the strait open - or force a US blockade - involves prolonged ground operations on Iranian territory, which makes it a difficult proposition for the US. GCC members want free shipping before any transit arrangement is negotiated for the Hormuz Strait. Asian consumers of oil and natural gas from the Persian Gulf may have to settle for bilateral deals with Iran for safe passage. China, the biggest buyer of Iranian oil, has the most influence to find a workaround to the Hormuz issue.

Tehran will use its geographical leverage to extract the best terms for cessation of hostilities with the US and Israel. Iran is seeking a larger role for itself in future shipping through the Hormuz Strait. It is difficult to reconcile its demand with current conventions over maritime trade. As the world's largest exporter, China has a big stake in ensuring shipping routes remain open. Trump shouldn't follow the blockade route.