As the US Navy announces a $4.1bn attempt to secure the Navy Marine Corps Intranet (NMCI), hackers have issued a warning that Navy websites are next on the list of targets.

The five-year project to secure the NMCI, which consists of 350,000 desktops and 200 networks, dispersed around the world, focuses on controlling virus outbreaks and killing malicious code.

The server infrastructure for the NMCI will be consolidated into a small number of server farms to minimise the network access points available to attackers.

Last year the Navy detected 23,662 hacking attempts on its networks, but since the kick-off of its multi-million security efforts, it has spotted only 125 breaches.

The Navy admits however, that most breaches could be avoided, as known vulnerabilities are often to blame.

Part of the new NMCI security focus will be keeping machines up to date with the latest patches.

But an email sent to vnunet.com from hacker, Apocalypsedow, warns that "the next target will be all the navy website. why? because the USA military like bombing and testing like in Puerto Rico. Stop the Exercise or we will permanent shutdown their network. Coming to your browser soon."

So we can expect hackers to be testing the mettle of the largest Defence Department implementation of public key infrastructure, used to restrict computer access as well as to protect and encrypt data travelling over the Navy networks.

Apocalypsedow offered some small comfort in his/her warning, though: "Don't worry the news sites will not get hit. We need you to tell the people how unsecure every OS and Firewall out there."