The top executives of soccer’s world governing body were sitting inside a castle in South Wales last weekend when they suddenly became distracted by their buzzing phones. They had gathered at an annual rules meeting to review tweaks to substitutions and video replay. But now the FIFA brass was being interrupted by a far more pressing matter.

The U.S., a co-host of this summer’s World Cup, had launched what it called “a major combat operation” against Iran, one of the countries due to play in