A serious cyber attack on a NATO country can activate Article 5 of the North Atlantic Treaty, stated NATO Secretary General Jens Stoltenberg.

In an interview with The Economist, Stoltenberg noted that NATO member states can intensify joint defense actions not only in the case of direct armed aggression.

"Cyber attacks can reach the threshold of Article 5 if they are serious. If it is large-scale, then we can apply Article 5 and respond not only in cyberspace, but also in other areas to protect NATO allies," Stoltenberg said.

He emphasized that Russia is the main threat in this area.