Washington

FOR the past several months, I’ve been wrapping up lengthy interviews with Washington counterterrorism officials with a fundamental question: “Do you know the difference between a Sunni and a Shiite?”

A “gotcha” question? Perhaps. But if knowing your enemy is the most basic rule of war, I don’t think it’s out of bounds. And as I quickly explain to my subjects, I’m not looking for theological explanations, just the basics: Who’s on what side today, and what does each want?

After all, wouldn’t British counterterrorism officials responsible for Northern Ireland know the difference between Catholics and Protestants? In a remotely similar but far more lethal vein, the 1,400-year Sunni-Shiite rivalry is playing out in the streets of Baghdad, raising the specter of a breakup of Iraq into antagonistic states, one backed by Shiite Iran and the other by Saudi Arabia and other Sunni states.

A complete collapse in Iraq could provide a haven for Al Qaeda operatives within striking distance of Israel, even Europe. And the nature of the threat from Iran, a potential nuclear power with protégés in the Gulf states, northern Saudi Arabia, Lebanon and the Palestinian territories, is entirely different from that of Al Qaeda. It seems silly to have to argue that officials responsible for counterterrorism should be able to recognize opportunities for pitting these rivals against each other.