There is very little that can be done to PREVENT attacks like this. The best we can do is have a plan for after.
Rank nonsense Barbara Streisand. Deport deport deport incarcerate incarcerate incarcerate, execute execute execute. YOU may not like that security, traded for freedom, but it can be done.
Let me see if I can split the baby.
There is quite a bit that can and should be done to prevent attacks like this. That won't prevent them all, of course. But many can be prevented.
Proper police and terrorism work, and coordination among government officials is one key. I believe this can and should be done within constitutional bounds. And one point to consider is that acts of terrorism (especially when planned and committed by foreign nationals) looks a lot more like an act of war than it does an ugly case of knocking off the corner convenience store. Preparations, prevention, and response maybe should look more like something military than like common criminal court.
Nor is there a strict and hard dichotomy between security and freedom. Indeed, we would do well to go back to Franklin's original words: "Those who would give up
essential Liberty, to purchase a
little temporary Safety, deserve neither Liberty nor Safety."
This full quote suggests that there are appropriate trades to be made.
For example, we all give up a little personal freedom when we choose to lock our doors and cars. I know there are still places where folks don't lock their doors and they still leave their keys in their ignition when parking the car. I grew up in such a place. But very few of us live in those places today. So we give up a little bit of non-essential freedom in exchange for a fairly significant amount of on-going security. Similarly for our personal choices to carry firearms. There is a certain amount of comfort and convenience (one might call it "freedom") that is surrendered by carrying a gun, in exchange for the significant security benefits we derive from doing so.
In contrast, relatively few of us choose to walk around all day in body armor (even where doing so is legal), or to drive an armored car. The costs of doing so (whether financial, comfort, or otherwise) simply do not justify the marginal benefits we'd derive.
Obviously, these are voluntary decision and not imposed by the government, so the analogy (like all analogies) is not perfect. But I think they highlight the trade.
Proper border security, with the minimal inconvenience of needing to show a passport or otherwise demonstrate a right to enter the nation seems to me to be a very minimal loss of freedom in exchange for a whole lot of security benefits. Obviously, those who believe in completely open borders and the free movement of anyone not actually wearing the uniform of an enemy army will disagree. But I think most of us recognize the need for nations to control borders. Limiting who can enter the nation limits who is in a position to wear a suicide vest into crowded theater.
Some import inspections are necessary for enforcement of constitutionally authorized duties and tariffs anyway, and--if done properly--could increase the difficult of smuggling dirty bombs, biological agents, etc into the nation to use in an attack.
Proper security around critical infrastructure, with actual redundancy where possible, and interlocks to limit how far damage propagates, imposes almost zero loss of freedom (except perhaps slightly higher utility costs), but prevents rank amateurs from easily inflicting grave damage on entire cities or regions.
Local police sharing information with federal agencies (and vice versa) when they come upon something that might indicate plans for terroristic activity violates nobody's rights.
Collecting meta-data on phone calls or emails from/to parties outside the USA is more controversial, and I have my concerns. But I'm not aware of anyone actually being prosecuted for regular crimes based on data obtained without a warrant. Maybe I just missed it.
In any event, somewhere between zero security and a complete police state is probably a nice point where constitutional rights are respected, but we're not being stupid in terms of leaving the proverbial front door wide open as we and the family go to bed for the night. I don't presume to know exactly what that looks like, but I suspect it means greater personal freedom in certain areas (RKBA/OC for example) and a bit more diligence on the part of the government in other areas (secure borders, tracking when non-residents overstay their visas, better background checks on immigrants, etc) couple with some changes to sentencing such as shorter sentences and more rehabilitation for certain low level crimes and longer sentences for serious crimes.
Finally, foreign policy matters. We could probably do with less "meddling" overseas, but a stronger response when we do get involved. Small numbers of special forces or even CIA field types might be better at finding and eliminating terrorist leaders while also presenting far less of a target and far less of a sore spot for locals than would large occupying forces. Part of this is probably a lot less support for Saudi Arabia coupled with a lot more domestic energy development including oil, natural gas, hydro, nuclear fission, and significant investments in fusion, with "renewables" where they make economic sense.
Charles