What should policymakers do in the aftermath of this kind of event? Nothing. This is a singular event, and not something that should drive policy. Unfortunately, you can’t prevent this sort of thing 100 percent.
By definition, news is something that almost never happens. The brain fools you into thinking the news is what’s important. So what should we be afraid of? Car crashes. Global warming. It feels insensitive to say it so close to the tragedy, but it’s true. Things so common that they’re no longer news — that’s what kills people.
The damage from terrorism is primarily emotional. To the extent this terrorist attack succeeds has very little do with the attack itself. Imagine if the bombs were found and moved at the last second, and no one died, but everyone was just as scared.