The message of the vengeful Taliban fighters was clear when they raided the offices of state-owned Radio Television Afghanistan (RTA) in Logar province, as the region south of Kabul fell to the jihadist juggernaut in mid-August.

An Afghan journalist describes being severely beaten as the Taliban destroyed his computer with an assault rifle, then trashed the television and radio studio.

“Shut up and don’t raise your voice!” a fighter warned the journalist. “If you raise your voice, we will kill you.”

For days afterward, he had nightmares that the Taliban...