US enemy's were any movement around the world allied with the Soviet Union or "potentially" allied -- meaning that they promoted even vaguely socialist policies.
So the US overthrew progressive governments in Iran, Guatamala, Chile and other places around the world.
But overthrowing governments was not enough. Socialist movements had the ideological allegiance of millions of people, so the US elites saw strategic gains in supporting a counter-ideological movement, conservative Islam, to mobilize a popular alternative and, where necessary, a military challenge to the socialists. (Notably Israel in alliance with the US had the same idea, and supported the growth of Hamas originally as an alternative to the PLO.)
Here is the deadly bottom line-- where people around the globe have been desperate and poor, they have looked for justice and a better life. The socialists promised justice in this world, but the US elites didn't want justice in this world; they wanted to protect the profits of US multinationals, so any movement calling for justice in this world was seen as too dangerous.
So they decided movements promising justice and paradise in the next world was the best way to compete for the loyalties of the poor and desperate. So Islamic fundamentalist movements were seen as good proxies that the US elite could support against its socialist enemies.
But when paradise is in the afterlife, that removes any limit to the violence such fundamentalist movements might promote, since fear of death is no longer a rational restraint on action.
This ties into Bill Allison's thesis that we are still fighting World War I (couldn't find the specific post) ... it would be nice to start a cross-blog discussion at this meta-level of analysis without getting drawn into the political substrata.