Unauthorised persons have succeeded in gaining access to plans for an American fighter aircraft project. The Wall Street Journal is reporting that computer spies have stolen "several terabytes" of data from the Joint Strike Fighter project. Since the plans relate to the design and the electronic system of the plane, government officials suspect that the stolen data could be of military relevance, enabling improvements in defensive measures against the jet.

The Joint Strike Fighter project is the Defense Department's most costly weapons programme to date. Developing the F-35 Lightning II jet has cost around $300 billion. Government officials familiar with the attacks have not put a figure on the damage caused by this unauthorised access in financial and security terms. The newspaper says the intruders were able to hide their traces so well that investigators have been unable to say precisely what data was stolen. The identity of the cyber attackers is a matter of conjecture.

The plans for the F-35 Lightning II jet being developed by Lockheed Martin are based, according to the Wall Street Journal, on 7.5 million lines of programming code, however, the most sensitive data, for example the code used for flight control, is stored on computers that are not connected to the internet. The cyber-spies obtained access to the data through insecure points in the networks of private companies involved in the project. Neither Lockheed Martin, Northrop Grumman Corp. nor BAE Systems, all of which are involved in the development of the fighter, were willing to make a statement about the data theft.

Other attempts to penetrate the computer systems associated with the Joint Strike Fighter programme have been observed over the last two years. Investigators believe that it is highly likely that the intrusions come from China, citing as clues the Chinese IP addresses and digital fingerprints that had been seen in earlier attacks.