http://www.telegraph.co.uk/news/newstopics/onthefrontline/4342884/RAF-ordered-to-shoot-down-UFOs.html

Pilots have apparently fired upon the unidentified objects without success since the 1980s, according to Nick Pope, who used to run the Ministry of Defence's UFO project.

"We know of cases where the order has been given to shoot down - with little effect to the UFO."

The MoD refused to comment.