As the Iran war escalates, the world's most vital chokepoints are coming under increasing threat. Iran's disruption of shipping through the Strait of Hormuz has already rattled global energy markets. Now, the Houthis could obstruct things further, launching a blockade on Saudi shipping in the Red Sea, and threatening to close the Bab al-Mandeb Strait. The two narrow waterways carry not only oil and gas, but also vast quantities of food and humanitarian supplies. Carl Skau, the acting Executive Director of the World Food Programme, has travelled to many of the world's worst humanitarian hot spots, witnessing both the scale of the suffering and the difficulties of delivering aid. He joins from New York. 

Also on today's show: author Colson Whitehead  

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