NATO said several of its websites were targeted by a "significant" cyberattack on Saturday in what appeared to be the latest bout of virtual warfare linked to the crisis in Ukraine.
The cyberattack on NATO was claimed by Ukrainian hackers and follows a similar attack on the websites of the Kremlin and Russian Foreign Ministry on Friday.
NATO spokeswoman Oana Lungescu said on Twitter that the alliance's websites had been hit by "a significant DDoS (denial of service) attack," but that the attack had "no operational impact".
In DDoS attacks, hackers hijack multiple computers to send a flood of data to the target, crippling its computer system.
Lungescu said experts were working to restore normal function but the websites remained down for hours and still could not be accessed by mid-afternoon on Sunday.
Lungescu did not say who was responsible for the attack, which was claimed by a Ukrainian hacker group called Cyber Berkut, the name given to the elite riot police involved in a street battles with protesters in Kiev.
In a statement on its website, www.cyber-berkut.org, the group said it had targeted three NATO websites over what it claimed was the alliance's interference in Ukraine and support of the "Kiev junta".
"We will not allow the presence of NATO in our homeland," said the statement, which could not be independently verified.
Friday's attack on the Kremlin and Russia's Foreign Ministry websites also brought them to a brief halt, along with the central bank's website.
"A powerful cyberattack is under way on the (Kremlin) site," a spokeswoman for the Russian president's press service said by telephone as security experts struggled to curtail disruption. All three sites were working later on Friday.
A group calling itself Anonymous Russia highlighted the Kremlin website's crash on Twitter, suggesting it may have been behind the attack.
The same group said it brought down the website in May 2012 in solidarity with protests against Putin on his return for a third term as president.
AFP - Reuters
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