One of the key elements in "fighting terrorism" I have noted is a reliance upon occupation and bombing campaigns of other places in a theory that fighting terrorism abroad means we won't have to deal with it here. This sort of logic lay under a lot of late 20th century foreign policy, through offshoring and other proxy fights with communist rulers across the globe on a theory that preventing the spread of communism to new countries would prevent it from spreading here. A more sensible understanding was that communism was never going to be that fertile in the US anyway, and much of Western Europe and other allies either and that all that was necessary was containment while the ideology destroyed itself. The mythology that Reagan won the Cold War has some pieces of merit, but at no point did he directly confront the USSR militarily in battle either (indirectly in Afghanistan and other places, yes). This should be instructive to understanding the limitations of the fighting abroad logic.
But what is really demonstrative is comparing the chaos caused by terrorism now to that of the 19th century anarchists (and some communists). This period spawned shootings, bombings, and political assassinations all over the world for several decades. The common cause was ideological, sometimes vaguely, and this inspired individual actors with guns and bombs to mayhem and violence. There was no other country to go invade or bomb to put a stop to it, as there is not really today either. The problem was growing and incubating within each country itself. It came from an idea, not a border. The problem now resembles this far more than the Cold War rubric that seems to dominate strategic action or what passes for strategic thought today. There is a "state" in the form of ISIS, which functions in a bureaucratic sense to administer territory, but the relevant feature of that state is not its ability to threaten us, or even its neighbours, with invasion and devastation in military conflict. It cannot do any such thing. It is the ability of this state's ideology to inspire action abroad to make small scale isolated attacks in an attempt to terrorize or at least annoy their perceived enemies. When or if it is crushed as an illegitimate state force, this result will be largely irrelevant. Other groups carry similar ideological beliefs (al Qaeda, Boko Haram, al-Shabaab, etc), and have inspired or carried out large scale attacks of their own. Conflict in military arenas is not the appropriate strategic realm on which to fight this problem in the first place, but appears to be the only dominant method we have considered executing.
It flows nicely from the "we must do something, this is something, let's do it" logic that I suspect pervades much public action. What we "know how do to do" is bomb locations or targets, and defeat enemies militarily with logistics, stealth, and firepower. Therefore that's what we're going to do by Jove. But almost all of which is useless against ideas. And typically involves a very expensive method of attempting with violence and force, and mostly failing, to stablize regions and governments that might spread and sponsor such ideas. This should be recognized as a dysfunctional method of response. Or at best, only a part of a response.
It is by now a common set of wisdom however that if they hit us, we hit them back. This is not a solution to most problems at the age of 4 or 5 in observing the play of children. It is hardly a solution to most problems for adults. Much less nation-states. A better analogy might work something like this. It is reasonable to take steps to deter a mosquito bite, to try to prevent mosquitoes from approaching you or an outdoor patio when one is in a summer or spring repose taking in the day. It is even reasonable to slap and kill the mosquito when it should bite you. It is not reasonable to decide after such a bite that you shall endeavour to exterminate any insects of any kind near you, most of which have done and will do nothing so remarkable even as to provide a small itchy patch of skin. This is generally what our responses look more like than the more limited "slap the mosquito" response.
In a foreign policy or national security explanation, we should be attempting to gather intelligence. On suspected terrorists, not on everyone, with a more strict limitation on what constitutes "terrorism". We should be taking reasonable but not onerous and super-expensive security steps. So some minor security screening to get on airplanes, with those having secured cockpits and alert but not paranoid passengers. And not rigorous and endless lines involving the removal of shoes and belts and toothpaste at great expense of time and energy (and lives) for little or no gain in actual security or deterrence of threats. We should be operating intelligence along the outer rim of groups that are deemed at risk of violent action (white supremacists, Islamic radicals, anti-choice radicals, etc), to try to identify and deter possible violence before it happens. But we should not be treating anyone with a generic Muslim heritage, members of biker gangs, or anyone using vaguely anti-government rhetoric as a potential terrorist either. Same with mental health issues and on down the line as subjects we have highlighted for prejudicial assessment in this way. We should not be deploying weapons of war to our own local and state police forces. These are of little use for most towns and cities in the project of anti-terrorism. They are of great use in the oppression of citizens local rights instead. And we should not be seeking to conduct bombing campaigns aggressively in other countries in the hopes of possibly killing "terrorists". Who are often insurgents, at least in parts of Iraq and Afghanistan, and no thus no threat to us here.
Violence that we would prefer to avoid is in this sense a disease. It is not solved by spreading it to more people than those who are already afflicted by it. Or afflicting yet more violence upon those already at risk of it.