But this threat is not new. If you watch the National tonight they have an excerpt from an upcoming documentary that talks about a pre-911 attack on a Phillipines Airlines flight to NRT that killed a pax. Liquid explosives were used.

The question is what screening is effective and what is not. I would argue that all (not 99.999999%, but all) of the enhanced screening that is going to inconvenience tens of thousands of pax is not going to be effective in finding that elusive needle in a haystack. it appears that all of the plots that have been averted have been foiled by good detective work and informants, not by airport screening.