The State Department has acknowledged that five U.S. personnel killed in Afghanistan, including 25-year-old diplomat Anne Smedinghoff, were on foot when they were attacked by a suicide bomber, and not in an armored vehicle, as officials had told bereaved relatives earlier this week. The violent deaths of U.S. diplomatic personnel — and the State Department’s changing account of how they died — harken back to the debacle in Benghazi, Libya, where Islamist extremists killed four Americans in assaults on the U.S. diplomatic compound on Sept. 11. “We are able to clarify at this point that they were