Iran's foreign minister Mohammed Zarif described the deal reached this week to lift economic sanctions on his country as a new chapter of hope. Iran has promised to limit its nuclear activity, but there are plenty of critics of the deal in some of the six countries which signed up to the agreement, notably in the United States. President Barack Obama is on a charm offensive to win over Congress, but it will not be an easy task, as the Economist Irwin Seltzer, from the Hudson Institute tells the BBC's Susannah Streeter.

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Gunners from the Armed Forces of Ukraine fire at Russian position with a 155 mm self-propelled howitzer 2C22 in the Kharkiv region on April 21, 2024. (Anatolii Stepanov/AFP via Getty Images)