[SkyMarshal]

>out of some abstract fear of "terrorism".

To be fair, it wasn't abstract, though one could argue that particular attack was a one-off that could never be successfully repeated. But there were other concerns of dirty bombs, anthrax, etc. at the time.

That said, it's truly a shame that the US abandoned Afghanistan to invade Iraq. Afghanistan seemed to have potential for nation-building had we not diverted and diluted our efforts with Iraq.