Shipping forecast: will America’s blockade work?

When the ceasefire between America and Iran collapsed after just three minutes of a press conference in Islamabad, Donald Trump’s administration pivoted to a strategy few had anticipated: a naval blockade of all ships using Iranian ports and coastal waters. Defense editor Shashank Joshi explains that the blockade is an attempt to achieve through economic strangulation what bombardment failed to deliver. But the gamble carries serious risks for global energy markets and America’s diplomatic relationships.

The blockade mechanism and its immediate test

America’s Central Command has announced it will impose a blockade on any ship—Iranian, Chinese, or otherwise—that originates in Iranian ports or passes through Iranian coastal waters. Under international law, blockades must be enforced impartially, which means the U.S. Navy will board and seize vessels regardless of their flag. The enforcement is expected to take place in the Gulf of Oman rather than the more dangerous Strait of Hormuz. A Chinese tanker, falsely flagged, was already heading out through Hormuz as Joshi spoke, providing an early test of American resolve.