How do the Taliban know these are Russian Federation intelligence agents?
Seems more likely that they are Americans of Russian speaking origin (ex-Soviet Union) who we colloquially refer to as the Russian Mafia even when they are Armenian or Ukrainian origin. These American criminals are known to work with the CIA's heroin production and trafficking business. So, when an honest US citizen in Afghanistan is disruptive to the criminal enterprise, they take out a contract on them and use specialists in violent crime and murder which is exactly why these former Soviets got the Mafia name in the first place.