Secretary of State Hillary Rodham Clinton says U.S. cyber experts hacked al-Qaida propaganda online in Yemen, changing ads that bragged about killing Americans into ads that showed the death toll of al-Qaida attacks against Yemenis.

Clinton says the cyberattack was launched by State Department specialists who patrol the web and social media to counter al-Qaida's attempts to recruit new followers. It was a rare public admission of the ongoing covert cyber war against extremists.

Speaking in Tampa, Fla., alongside special operations chief Adm. Bill McRaven, Clinton said the effort is part of a multipronged attack on terrorism that goes beyond raids like the one that killed Osama bin Laden to include diplomats working alongside special operations forces to shore up local governments and economies and train local forces.