It was just one of hundreds of arguments between American and Iranian officials as they tried to hash out what may prove to be one of the hardest-to-negotiate arms control agreements in history. But it spoke volumes about how two countries that so deeply distrust each other managed to strike a tentative deal. After President Obama revealed the existence of a secret, deep-underground enrichment operation near the sacred city of Qum in late 2009, the White House demanded that it be dismantled and closed. In defiance, the Iranians stuffed the facility, called Fordo, with 3,000 centrifuges — a huge issue for American and Israeli military planners because it is impervious to all but the largest bunker-buster bombs. Iran ’s supreme […]