Its rather obvious, but as no one has pointed it out on this thread, then please let me!
Airports are large, complicated facilities. Access to them is neccessarily unrestricted in order for the public to make use of them. There are a great many of them.
It is not possible, by ANY means to raise Airport Security to a level which will stop very determined men from doing what the want to do.
The only way to achieve this is by removing the very real grievances, by political means, which drive the terrorists to such extreme acts.
Unpalatable I know. But fact.
Thankyou. Now feel free to return to stories about the time you went through security and they didn't spot your pen knive.