It is a peculiarly Western narcissism that drives us to attribute the motivations of extremist Islamism wholly to the (in)actions of Western governments. Some seek to lay blame at the feet of our leaders over the Iraq invasion, or the support of the mujahideen in Afghanistan, or Israel, or European imperialism or poverty. This excludes the possibility that the Muslim world ("Ummah Al-Muhmini") - spanning much of Africa and Asia across 1500 years - is sufficiently complex, diverse and conflicted to initiate and sustain its own motivations. One such example is the desire of a significant minority of Islamists to impose a Caliphate under Sharia Law ("al-ummatun wahid") - a Taliban-style society running from Libya to Indonesia.
It's natural to seek understanding of a complicated world through the lens of our own experience. But when we deny the reality of a billion people it becomes a dangerous, indulgent conceit.