OPINION by Gideon Rachman for the Financial Times

Donald Trump's domestic critics have often compared him to a mafia boss. James Comey, who Mr Trump fired as head of the FBI, said that dealing with the US president reminded him of his earlier career, "as a prosecutor against the mob".

Mr Trump made his career in construction in New York and casinos in New Jersey, which may explain why his mannerisms seem strangely familiar to fans of The Godfather or The Sopranos.

But this is not merely about style. The president's way of conducting foreign policy also seems to owe