In 2004 it was discovered that parties unknown had been secretly monitoring a hundred of Greece’s top politicians and bureaucrats. An article from 2011 reveals that,
According to what sources told Kathimerini, the experts found that a mobile phone connection that had been purchased in the name of the US Embassy in Athens was used on one of these phones. Sources said that Dasoulas is now investigating whether any suspects who are not protected by diplomatic immunity could face charges.
Ericsson, which supplied the telephone exchange that was hacked into, and Vodafone, which was the service provider, were both fined by ADAE in 2007 for failing to protect the privacy of those who had their phones hacked, which included the head of the National Intelligence Service (EYP), several ministers and members of the armed forces, but the Council of State later cancelled these penalties.
The followup, of whether the Americans were actually involved, is ongoing as far as I can tell. Regardless of the culprits it’s instructive that even the head of the intelligence service was successfully targeted. We need to be mindful of how surveillance technologies are deployed in our communications networks, not just because we worry about how our own government might use the technologies, but also because of how other third-parties might use the technologies against the citizenry.