The US Army has retreated from Windows NT on the hosting server of its website and deployed MacOS because it believes it to be more secure from cyber-terrorists.

The Army will use a Mac system running the WebStar web server from StarNine Technologies. The decision may have been prompted by an incident in June this year, when the site was the target of a hacker group called Global Hell. At the end of August, FBI agents investigating the case arrested a 19-year-old US man.

Christopher Unger, website administrator for the Army home page, said the move was about creating a secure site. He said MacOS was chosen because it didn't have a command shell, doesn't enable remote logins, and "is more secure than other platforms".

He added the Army had based its decision on advice from the World Wide Web Consortium, which is committed to developing standards for the internet.

Simon Gardner, professional services manager for security consultant Secure Computing, said that there is nothing intrinsically more secure about MacOS. But he added that its smaller installed base meant that it had received less attention from hackers over the years. "It's less well known by hackers, so it's a kind of security through obscurity."

He would not advise his clients to follow the Army's example, as moving to a completely new OS required a lot of work and re-training. "You're better off sticking with what you know. Any system is going to be compromised eventually. There is no such thing as 100 per cent security."

Mark Tennant, Microsoft NT server marketing manager, could not confirm the Army's action but claimed that Window's share of the OS market completely dwarfed that of MacOS. He said this meant that it was statistically more likely to come under cracker attack.