An American armored vehicle on Thursday barged unannounced into the wreckage of the Doctors Without Borders hospital in Afghanistan that the U.S. bombed earlier this month, reigniting tensions between Washington and the aid organization over the Oct. 3 attack. Doctors Without Borders said the move violated a commitment by U.S., NATO and Afghan investigative teams to inform Doctors Without Borders before taking any steps involving the aid organization's team or facilities. The intrusion may have damaged evidence at the site that could help explain the bombing, the organization says.