The bridge they ran away across was a land one rather than air. The date was February 15, 1989. 47 years have passed since the fall of Saigon, and the USA is still here. The USSR lasted barely two after their troops left Afghanistan with their tails between their legs...
Sorry to bust your bubble but in 1985 Gorbachev declared withdrawal by 1989.
Nobody left with tail between legs, that is what the US force did recently.
Pro-Soviet government lasted four more years, and largely succumbed after the funding ended to them, but the CIA still funded Taleban.