It manages America’s defense attaché system, operating out of U.S. embassies and consulates around the globe. It counts more than 16,500 military and civilian employees in 139 countries, with hundreds in Afghanistan. An unknown number work undercover. Its size has more than doubled since 2000, partly because of the restructuring of military intelligence, and many more employees are deployed abroad. Today, more than half of DIA’s staff is posted outside of Washington, compared to less than a third in 2000. The agency is bolstering its clandestine operations overseas.