continuing flubbed post...
...see Dan's post below about Vozrozhdeniye, the former island in the Aral Sea where the Soviets conducted some of their germ warfare research.
I'd say this is a likely candidate for the source of the anthrax.
The Aral Sea straddles the border between Kazakhstan and Uzbekistan and is about 1200 km from Kabul, as a point of reference.
sp