"We cannot know how the war will develop; only that it will. It will be quite unlike previous world wars. We can only observe that we are now in transition from the terrorist stage, to the guerrilla warfare stage. I can only guess, but would think the next threshold will be crossed when a country, most likely Iran, brings true "weapons of mass destruction" into play. The word "threshold" could mislead. Each new stage adds another layer, so that the terrorism will continue, joined to guerrilla war; and then both will continue, with WMD added.
Does that sound alarmist to you? If so, I can only reply, wake up, gentle reader. The very people who guard you in your sleep are alarmed on your behalf."