Reason. Sounds like he’s trying to catch the eye of the elusive-yet-ubiquitous Trump voter by being the first demagogue out of the gate in the wake of the Brussels attack. Theories of how to prevent terrorism are futile, however. There is no way to prevent terrorist/guerrilla attacks from the top-down. How do you stop a lone wolf terrorist before he strikes? He doesn’t use encryption, because he doesn’t talk to anyone. When a small group of men (and women!) sincerely plot to take the lives of sitting ducks, and are willing to sacrifice themselves in the process, they have the odds stacked in their favor. Short of transforming society into a massive prison, there’s no way to prevent all attacks. Soft targets are everywhere, ripe for the picking for someone bent on a massacre. All this War-on-Terror baloney is nothing more than security theater, it’s government heeding Rahm Immanuel’s dictum that one should never let a crisis go to waste.
Terrorism is scary, unpredictable, and the people want to be kept safe. So a vast Surveillance State is erected on top of this fear, and, while being extremely expensive and ineffective, somewhat alleviates the fear of the masses. So the Warfare State gets everything it wants: endless war overseas, massive Surveillance State at home.
Of course, ending overseas intervention would halt the creation of terrorists that become the excuse for the Surveillance State in the first place. But that would lead to a diminishment of government power. No, the Warfare State needs the terrorism to justify its existence. Brussels, Paris, etc., provide the fuel for the paranoia that will keep the War on Terror gravy train rolling for another decade.