The NATO Joint Cyber Defense Center of Excellence, established in Estonia in 2008, is engaged in such tasks. By the way, it is precisely the specialists from this Center who take the initiative to equate a cyber attack with an armed attack with all the ensuing consequences. According to Article 5 of the NATO Charter, in case of aggression against one of the members, the alliance is obliged to take retaliatory steps. That is, in the event of an external attack on the network infrastructure of a NATO member state, the alliance neutralizes the threat, and then conducts cyber-encroachment on the enemy: disables troop control systems, blocks the work of state institutions, cuts off electricity, etc. In general, everything is like in a real war with tanks and airplanes, only using computers and the Internet.
Returning to the teachings of Steadfast Jazz - 2013. While on the Polish test sites, helicopters and artillery of NATO reflect the aggression of a potential enemy, the Tallinn Cyber Defense Center conducts a cyber operation, during which several Ukrainian and Latvian sites were hacked to indicate their security gaps.
Probably, the activities should have been carried out in an artificially created information system, but because of an error, instead of duplicates, the real websites of large state organizations were hacked (http://news.pn/ru/incidents/90812). It is indicative that the operation was carried out against a non-NATO state, that is, it was actually offensive in nature.
However, some media outlets write that this incident is related to the recent activity of Ukrainian Anonymous. Hackers who oppose any alliances with the EU, NATO and Russia hacked several Russian and Polish resources, then attacked the website of the European Investment Bank and the website of the Estonian Ministry of Defense. Apparently, the topic of the possible signing of the Association Agreement with the EU is very acute in Ukraine even at the level of the hacker community.