Ken Burns is in your future

Charlie Wilson's War is a pretty great movie about that, starring Tom Hanks, directed by Mike Nichols and written by Aaron Sorkin, although it's more of a political satire and plays it fast and loose with the historical details.

The Soviet-friendly Afghan government wasn't a) progressive and b) wasn't secular. The government is explicitly Marxist-Leninist who oppressed and forced people to drop their religion as part of state atheism.

The progressivism and secularism you refer to was during the kingdom era before being overthrown by the communist Afghan military. The more liberal attitude is only contained in a bubble in the capital city of Kabul. The rest of 80% of Afghans are still religious conservatives living rural and in poverty. An Afghan female former politician lamented not seeing this because she grew up in liberal Kabul.

Also more importantly, it's a misconception that the US helped the Taliban. The mujahideen was composed of various factions, some are secular, some are conservative, while some are more Islamists. But, the ultraconservative elements only came later in more definite form under the Taliban, which defeated both the secular and conservative forces.