In a rare public admission of the covert cyber war against extremists, the US Secretary of State said cyber experts based at the State Department hacked Yemeni tribal websites.
"Within 48 hours, our team plastered the same sites with altered versions of the ads that showed the toll al-Qa'ida attacks have taken on the Yemeni people," she said.
"Extremists are publicly venting their frustration and asking supporters not to believe everything they read on the internet."
Mrs Clinton described the cyber effort as part of a multi-pronged attack on terrorism that went beyond attacks such as the Navy Seal raid that killed Osama bin Laden to include the propaganda battle, and the longer, slower campaign of diplomats working with special operations troops to shore up governments and economies and train local forces.
