and advertising. The 10-week course has been "certified" by UK spy agency GCHQ. But some security experts raised questions about the need for the course and the intent behind it. Previously the jets had only been seen by bloggers. Naturally China will be presenting plenty of other military hardware this week from attack helicopters to seaplanes. And with China set to become the world's biggest aviation market in the next decade, the show is an opportunity for Beijing to demonstrate its ambitions in civil aviation as well as defence. "Unfortunately once again the few ruin it for the many," wrote Jesse LaBrocca, founder of Hack Forums, in a message explaining why the section was being closed. The "recent events" are likely to be the attacks of 21 October