One's perception of the continuing threat to commercial aviation from terrorism is relative isnt it?Europe dint have a 911,so these measures are seen as paranoid.Talk to the relatives of the crew who had their throats slit on that fateful day,and its seen as a measure long overdue.
I dont think the US takes any satisfaction in "interfering" with the sovereignity of your national airlines,but the directive is only aimed at those airlines entering US airspace.Recent events have all but confirmed that these people want a rerun of 911.The US is not about to let a bunch of left-wing whingeing Euros prevent them taking whatever measures are required to stop another 911.To all those rational people across the pond who understand that Air Marshalls are NOT dangerous,and that they are needed in this day and age,we say thank you for helping us to keep America safe.