NATO is this week carrying out its third cyber defence exercise since 2008, involving 24 of 28 alliance members, plus Austria.
The Cyber Coalition 2010 exercise simulates multiple simultaneous cyber attacks against NATO and alliance members to test their strategic decision-making process.
Cyber warfare is one of five sections within a new NATO division against emerging security threats that was created in August.
NATO has been working on improving its cyber defences ever since leaders asked the organisation to improve security for its computer networks at a summit in Prague in 2002, head of NATO Cyber Defence and Countermeasures Branch Suleyman Anil told AFP.
Cyber strikes against Estonia in 2007 and the discovery of the Stuxnet computer worm this year, have spurred efforts to protect NATO networks, including a cyber defence research and development centre in Tallin and a rapid reaction team to help any NATO member after a cyber attack.
In 2009, NATO signed a memorandum of understanding with seven alliance members on data sharing and procedures to follow in case of a cyber attack, but still has to reach similar agreements with remaining members and only expects to achieve 100% protection of all its networks by 2013.