Some of Nato’s public websites have been subject to a series cyber attacks, which have been linked to Ukranian hackers, according to reports. Sky News reports that a group that calls itself “cyber berkut” has claimed that the attack has been carried out by patriotic Ukrainians angry at what they believe to be Nato’s interference with their country. The claim, which was made on their website, has not been independently verified. The main Nato website (www.nato.int) along with, Nato Parliamentary Assembly site and Nato Cooperative Cyber Defence Centre of Excellence, were the ones targeted. In a tweet Nato spokeswoman Oana Lungescu said Nato had been hit by DDoS (denial of service) attacks but that none of its essential systems had been compromised, adding that experts were working to rectify the problem (see below).All three sites had been taken down, but Lungescu later tweeted that the Cyber Defence Centre of Excellence site was back up.