"The initial stability of Najibullah’s government suggests that Afghans will assume responsibility for the fate of their government when the foreign footprint in their country has been sharply reduced -- but only if an outside patron is prepared to supply and equip Afghan forces. The central government in Kabul is strengthened when it sends gifts to the provinces rather than collecting taxes from them. But someone has to pay for this. The United Kingdom lavished resources on India in the nineteenth century; the Soviet Union sent billions of rubles to Afghanistan. Is Washington prepared to play such a role today?" Nikolas K. Gvosdev in Foreign Affairs
Bribery, patronage, and Pakistani support.
but for how long? Gvosdev himself noted that Najibullah's government ultimately failed.