Pakistan is run by absolute morons, At the height of the US presence in Afghanistan, when there was limitless money being poured into Afghanistan by the US, Pakistan should have negotiated a funding of a hardened border wall on the Afghan Pakistani border, completely mined the area thoroughly and set up manned watch towers along with surveillance equipment, drones and other infrastructure. It would have stopped the TTP being able to cross over as well and stop the drug flow and refugees from Afghanistan coming into Pakistan, and this would have all been done with US money, as the US was eager to have cross border militancy stopped in both directions, and it would have even twisted the arm of Kabul to go along with the proposal. Instead they waited to start fencing only when the US started losing interest in Afghanistan and was fatigued and wanted to dedicate resources in the fight against China.