In a classic case of 'closing the barn door after the horse has bolted', the day after the Christmas Day bombing attempt on flight NW253 we of flight DL9 bound for Atlanta were subjected to two hours of delay at Heathrow airport for extra frisking. Then, at Immigration at Atlanta, my fingerprint machine appeared not to work, leading to my being taken to another room and left forlornly for two further hours, thus putting paid to any futile, lingering hope of making the connection to Knoxville.
Now....here are some, possibly relevant, facts...
.....anti-terrorist wars have already cost the US at least $800 bn and finally will have cost an estimated $2-3 trillion,
.....of the order of one hundredth of the above amounts (i.e., ~$10 bn) has so far been spent on improved airport security, and this not always wisely.
.....a "puffer machine" capable of detecting explosives such as that allowed on NW253, costs about $160K; sniffer dogs presumably less.
Maybe I'm wrong, but by my estimation, given the money already spent, which is still only of the order of 1% of the cost of the wars, enough puffer machines etc could have been installed, sniffer dogs bred and trained and friskers hired to effectively, easily, rapidly and quickly process all international flights into the US.
...and I wouldn't have missed my flight to Knoxville.