We're not allowed to stop it. Drugs are their cash crop, and their way of life. We're told to overlook their poppy fields. ADTs try to get them to grow something other than poppy, but poppy is pretty profitable.
Not only that, the Afghans' way of life is centered around armed conflict. For over 1100 years, what was a beautiful country that housed many centers of Hindu and Buddhist learning and was home to several Greco-Indian kings, has become a battlefield soaked with the blood of millions.
The Afghans primary narrative is that of war; warlords ruled the roost there since the invasion of Islam in the 8th and 9th centuries CE. From there, Afghan rulers themselves invaded India (present day Pakistan and India) in the 12th century CE and established the Delhi Sultanate, laying the groundwork for the barbaric Mughal era.
In some ways, it is hard not to think the current state of affairs in Afghanistan is the result of karma; their barbaric invaders destroyed, raped, and committed genocide against millions of Hindus and then Buddhists, destroying the greatest and earliest universities in the world; Nalanda and Takshashila. And more recently, after the bombing of the Bhamiyan Buddhist statues by the Taliban, Afghanistan has been ravaged by war.
The only positive solution to the Afghan problem is that India should take back the land that was once part of it; Bharat. For then, with the infusion of Hinduism, Afghanistan will arise from the pits of torment and bloodshed. They already love Indian food, "bollywood", and other Indian culture (superficial things). If they dive deeper into the culture they once were a part of, they will find peace instead of war.