US cyber experts launched a huge attack on an al-Qaeda's affiliate and replaced propaganda with er different propaganda.
US Secretary of State Hillary Clinton told AP that the sites were based in Yemen and were full of material that bragged about killing Americans. The US hackers replaced it will information about civilians killed in terrorist strikes.
It is one of the first times that the US has admitted carrying out a covert cyber war against extremists.
When al-Qaeda recruitment propaganda appeared on tribal sites in Yemen, Clinton's team had turned the sites over within 48 hours.
In a speech to the Special Operations Command in Florida, Clinton used the hacking operation as an example of growing counterterrorism co-operation between the State Department, intelligence agencies and the military.
She said that such operatings were starting to have an impact in Yemen because al-Qaeda are publicly venting their frustration and asking supporters not to believe everything they read on the internet.
It does seem to be giving Al-Qaeda some credibility problems when it comes to recruiting.
The hacking was conducted by the Centre for Strategic Counterterrorism Communications, based at the State Department, Clinton said.
The State Department's activities are part of online efforts to stem the spread of radical Islamist ideology that stretch back at least a decade.
Of course there are no plans to conduct a similar campaign against Christian fundamentalists and right-wing groups in the US. That would be against Free Speech.