Ian W, a bit of knee-jerk there. If you read what I said, and what I replied to, you might have understood that I was talking about autonomous pilotless aircraft rather than remotely-piloted UAS such as the Global Hawk, and about interception of civilian aircraft by military aircraft in normal airspace not war-zone (e.g. in the case of a security concern, or cases like Helios 522), which is never done by UAS!