Nato has warned that any future cyber-attack against any member state will trigger the group's mutual defence clause.
Nato's warning follows last week's 'Petya' malware attacks that shut down the central bank and many government offices in Ukraine.
Days after the FBI, Europol, and the UK's National Crime Agency announced a joint investigation into Petya malware attacks that crippled institutions in Ukraine and elsewhere, Nato has announced that any future cyber-attack against any member state will trigger the group's Article 5 [mutual defence clause].
Nato will treat future cyber-attacks against member states as conventional military assaults and will respond accordingly, said the group's secretary-general Jens Stoltenberg.
"The attack in May and this week just underlines the importance of strengthening our cyber defences and that is what we are doing. We exercise more, we share best practices and technology, and we also work more and more closely with allies," he said.
“Nato helps Ukraine with cyber defence and has established a trust fund to finance programs to help Ukraine improve its cyber defences. We will continue to do this and it is an important part of our cooperation,” he added.
Ukrainian authorities had confirmed last week that while they had initiated an investigation into the cyber-attack, they were reasonably convinced that the attack was sponsored by Russia. Despite being assisted by Cisco, the authorities have not been able to pinpoint the source of Petya cyber-attacks so far.
The Petya cyber-attack had destabilised operations in banks, media organisations, communication facilities, transport, telecommunications, and energy departments. Among the hardest hit were Ukr telecom, Dniproenergo, Ukrzaliznytsia, Kiev -Boryspil Airport, and the Cabinet of Ministers of Ukraine. Popular aircraft manufacturer Antonov was also reportedly hit.
In other news, DLA Piper, a law firm whose email account was knocked out following the Petya cyber-attack, has confirmed that it has regained control of its email and that other systems were being restored.
"Following the widely reported malware incident that occurred on Tuesday 27 June, we have brought our email safely back online, and continue to bring other systems online in a secure manner. The firm took immediate steps to contain the threat, and we have seen no evidence that client data was taken or that there was a breach of confidentiality of that data," said the firm in a statement to the media.