IS is not supported by any country, JECE. They're entirely self-sufficient from oil revenues. Literally every country is out to kill them (except Turkey who values the lives of their hostages and hates the Kurds too much).
Also, I was referring to the Taliban that the US fought from 2003-present. The "real" war in Afghanistan. As far as I recall, they didn't have artillery, armored vehicles, aircraft, or any other conventional weapons. As for the Viet Cong, I believe you may be confusing them with the North Vietnamese Army - a conventional force with artillery, planes (which were very successful), anti-aircraft guns, tanks, etc. The Viet Cong didn't have that, and even if I did, I qualified my statement by saying "in terrain so unforgiving where conventional warfare was impossible"