A state-of-the-art monitoring technology will allow Nato to instantly spot anybody trying to hack into its systems.
Nato's Communication and Information Systems Services Agency is protecting the alliance's network of thousands of computers with Guidance Software's EnCase Information Assurance technology.
The system provides an immediate snapshot of any intrusions and forensic-level analysis across its network, which spans thousands of miles.
Nato's Computer Incident Response Capability (NCIRC) unit has deployed a large-scale cyber-defence project combining intrusion detection and prevention systems, security information and event management and automated incident response.
Ian West, director at the NCIRC technical centre, said this will significantly enhance Nato's ability to counter today's online threats and attacks.
West said in a statement: "[This] has enabled us to do in seconds what used to take us weeks.
"It delivers a unique capability at our fingertips that would have otherwise taken massive in-house resources to achieve," West added.