New Delhi, April 14 -- WHEN AMERICA and Israel began their war on February 28th, it was widely expected that Iran would choke off shipping in the Strait of Hormuz. Few would have predicted that, less than two months later, Donald Trump would impose a blockade of his own, targeting traffic to and from Iranian ports and coastal areas. It went into effect on April 13th. Mr Trump hopes economic strangulation might force Iran to open the strait where bombardment has failed. It is a dangerous gamble that could compound the global energy crisis and lead to fresh escalation.

America's rationale is simple. Iranian threats have drastically reduced tanker traffic through Hormuz. But Iran has continued to export its own oil, albeit at reduced levels...