As sad as it is, I think the responses will be: - we need more surveillance rights and money for the secret services - we need more police and higher spending - and possibly bomb some country (Syria is en vogue) What won't be said is: - How come this happens again without anyone having seen it coming? - What does it say about the success of the Western anti-terror foreign policy adopted ~2001?
It's not like you can say "yeah, we saw that coming and let it happen." Because THAT, sure as hell, will not fly with the people. And "yeah, we saw it coming and stopped it" is questioned as just posturing. When people say "scanning individuals in airports makes us no safer," what are they comparing it to?
Is it that they doubt the effectiveness because people are still getting killed by terrorists in planes? No. It's because there are no attacks, so they have no data to say "yeah... it's been effective."