“I think we need to pull out and let them kill each other.”
OMG. I beseech you to learn about radical Islam and its “God-given mission”. It’s not about killing each other, that’s just distracting fallout, it’s about killing ALL non-Muslims (Israel AND the West being top priorities)and re-establishing Islam as the power dominating the planet. Read their teachings, listen to/read the experts and scholars on this, of which there are many (and a significant of former Muslims themselves).
Because we made the mistake of pulling out of Afghanistan immediately after defeating the Russions there, Bin Laden and Al Queda along with the Taliban, established a firm foothold and safe haven in our void. It haunts us to this day, but to make the same error this time quite possibly will be fatal.
I don't know where you get this "re-establish" stuff. Islam was was established after Christianity, and long after Judaism.
Historically speaking we were never in Afghanistan, were were just arming them.