Why and how is US blockading Iranian ports in Strait of Hormuz?

(Jake Laphamand, Anna Lamche – BBC) The US has intercepted and seized an Iranian-flagged cargo ship, after the Trump administration started a naval blockade of maritime traffic entering and leaving Iranian ports earlier this month. On Sunday, Trump said the US Navy had intercepted the ship, called the Touska, in the Gulf of Oman. Earlier this month, US forces announced they would intercept or turn back vessels travelling to or from Iran’s coast. Washington said ships coming or going from elsewhere would be allowed to pass through the Strait of Hormuz, a critical waterway off Iran’s coast that Tehran effectively closed in response to US-Israeli strikes. The US is using its fleet of naval vessels to control access to Iranian ports, and in turn restrict Tehran’s ability to profit from oil exports in an attempt to put pressure on the country. The blockade comes after negotiators from both sides failed to reach a deal to end the war, which began on 28 February but is currently under a two-week ceasefire. – Why and how is US blockading Iranian ports in Strait of Hormuz?