The problem here is a fact that we have pointed out many, many times at Jihad Watch: there is no reliable way to distinguish jihadists from peaceful Muslims. There is no Islamic authority (with the arguable exception of the Spanish ulama) that has declared that Muslims who hold to the theology and ideology of Osama bin Laden are not true Muslims and are not welcome in their mosques. Making this even more difficult is the doctrine of religious deception founded on Koran 3:28. Thus the Afghan police authorities couldn't have kept Taliban loyalists out, even if it tried -- and it is unlikely that it is trying. This is something for the learned analysts to ponder not only as it concerns our policies in Afghanistan, but numerous other policies as well, including immigration, the language used in defending ourselves from this threat, and more.

"Five British soldiers killed by rogue Afghan policeman...

http://www.jihadwatch.org/2009/11/afghanistan-rogue-policemen-murder-fiv...