You can sometimes end up with some strange de facto allies in a war.
As far as "terrorism" is concerned the Soviets were into that at the time. Later on, during the Afghan civil war following the Soviet withdrawal, you had terrorism vs. terrorism by a wide variety of groups, some Islamofascist, some dopers, some left over military groups, etc.
There were a lot of Arab terror groups during the Carter and Reagan years. Mainly they were marxist in orientation and often, though not always, working with the Soviet Union. Even one of the Irish terror groups had marxist ties, which is a bit of a surprise.
Claire Sterling’s book The Terror Network was a good source of information on terrorism of that era. Maybe a great source since it’s still hated by those who insist it was CIA propaganda, and it was published in the mod 80s.
The group that Osama derives from is the Egyptian Brotherhood and dates back to the late 1950s. It is radical Islam in nature. The Brotherhood is the movement that assassinated Anwar Sadat over the Camp David Peace Agreement. They are feared and hated by Arab leaders as much as they are by the West.
Steve Emerson was warning about this movement before 9-11. I believe he managed a personal interview with bin Laden in the wilds of Yemen for his book, which I think is American Jihad. He has a couple of books with similar names and I don’t recall which is his earliest. Well worth reading especially since he was writing before 9-11.