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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An Air Force Global Strike Command unarmed Minuteman III intercontinental ballistic missile launches during an operation test on February 23, 2021, at Vandenberg Air Force Base in California. (US Space Force)