Sir: The Peshawar tragedy has reignited the resolve of the nation to root out terrorism once and for all. Pragmatic and effective measures to wipe out terrorism need deeper analysis. One model helpful for understanding such complex problems is the iceberg model. If we apply this model to the terrorism problem, we could say that at the tip are events we see or hear about the happenings in the world. If we see just below the waterline, we often start to see patterns, or the recurrence of events. Patterns are important to identify because they indicate that an event is not an isolated incident. Like different levels of an iceberg, deep beneath the patterns are the underlying structures or the root causes that create or drive these patterns. Finally, at the very base of the iceberg are assumptions and worldviews that have created or sustained structures in place. The important thing to understand is that in solving problems, the greatest leverage is in changing the structure — applying deep ocean currents to move the iceberg, which will change the events at its tip. This will be only possible if the government takes a very firm stand on madrassas, Friday sermons and the syllabi in schools in addition to army action. Dr Najeeb A Khan Islamabad