I understand all along the durand line sorta remains a soft border despite recent fencing and patrolling efforts. Its been that way for a millenia predating the modern nation states of the region, very difficult to enforce.. terrain bhi mushkil hai, impossible to do an unbreachable and always guarded border, or it may be cost prohibitive with tribals on both sides opposing it.
Even during the 'enduring freedom' days, it was a major headache for both Pk fauj and ISAF..
Osama bhi wahi se aaya tha, from tora bora
they did their own clearing op after the school tragedy with op Zarb e Azb.. fir bhi ni rok pae bad guys movement... nasty problem to have.
kinda similar to our lungi infestation, good thing those kamzor hilsakhors are nothing like the taliban and crew.