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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The P4 laboratory, on the campus of the Wuhan Institute of Virology, in Wuhan, in China's central Hubei province. (Hector Retamal/AFP via Getty Images)