To understand what Americans are fighting, it is necessary to first understand that we are not fighting a "War on Terror." We are no more fighting a "War on Terror" than we fought a "War on Kamikazes" in World War II. Of course we had to stop Kamikaze attacks, the suicide crashing by Japanese pilots of airplanes into American war ships. But we were fighting Japanese fascism and imperialism.
The same holds true today. We are fighting Islamic fascism and imperialism (though surely not all Muslims).
The parallels are almost as extensive as any historic parallels of two different phenomena can be. The fascist Japanese regime aimed to subjugate much of the world, Asia in particular, and it used whatever violence it could think of without any moral constraints. The fascist element within Islam wishes to subjugate the entire world using whatever violence it can think of without any moral constraints.
Of course, there are differences: Imperial Japan was preoccupied with dominating Asia, while imperialist Islam aims to dominate the whole world. And imperial Japan did so as an outgrowth of nationalism, while imperialist Islam does so from an outgrowth of a trans-national religious ideology.
Islamic terror is a tactic of an ideology. That ideology can be called "radical Islam," "militant Islam" or "Islamist," but it is rooted in Islamic imperialism.
With a background in religious studies and having studied Arabic and Islam, many listeners have called my radio show asking me if I consider Islam to be inherently violent or even evil. From 9-11 to now, I have responded that I do not assess religions; I assess the practitioners of religions. Why? Because it is almost impossible to assess any religion since its own adherents so often differ as to what it is. For example, is Christianity the Christianity of most evangelicals or that of the National Council of Churches? On virtually every important moral issue, they differ. The same holds true for right- and left-wing groups within Judaism.
Nevertheless, one can say that from its inception, Islam has been imperialist. My working definition of imperialism is that of University of London professor Efraim Karsh, whose recent book, "Islamic Imperialism" (Yale University Press), is one of the few indispensable books on Islam.