A bitter dispute over forced assignments to Iraq has erupted inside the State Department with diplomats taking decidedly undiplomatic potshots at one another. The latest public salvo came Tuesday with a harshly critical post on the department's official blog in which a foreign service officer in Iraq skewered those who spoke out against the prospect of ordered tours of duty at the U.S. Embassy in Baghdad and outlying provinces. The message, titled "A Letter From Iraq to My Overwrought Colleagues," accused opponents of being spoiled elitists whose revolt against so-called "directed assignments" is embarrassing. "To my vexed and overwrought colleagues,...