You seem to think that the fence is there to keep all out.....As has been proven on several occasions over the years, if someone is determined they will breach the fence in one way or another.
Common sense says it is a deterrent not a barrier, Had they entered from the controlled area and attempted access to the restricted area the chance of them being seen would be increased greatly. Not something they wanted to risk obviously.
At the end of the day no one can eliminate the risk only mitigate it. Get over it and stop letting every tin pot lunatic in the guise of a terrorist win.....
