I have a different opinion, Its only a conspiracy theory that US helped Al-Qaeda. The main Al-Qaeda group was eliminated by US coalition attacks. Al-Nusra fought and kicked out every pro-US group in Idlib, even they attacked pro-Turk groups. Even Al-Nusra's top leadership other than Joulani was also killed by US-coalition airstrikes. Russian couldn't kill those leaders because Russia have a way less target bombing policy than US. I have no sympathy for any power but I just want to present the facts.
Please check this link as it shows almost all of Al-Qaeda figures were killed by US.
https://en.wikipedia.org/wiki/Khorasan_group