The world and especially entities of any kind, that are trying to force any one point of view on the rest of the planet, have to stand down! Also, acknowledge their mistakes. Failure to ever acknowledge wrongdoing or mistake creates a sort of vacuum into which extremist ideas proliferate.
A moral society cant be faked, nor can democracy or legitimate governance be faked.
It has to be real, in other words, not itself be extremism, to have the effect of nullifying extremism.
This return to honesty is really needed. We have to face the fact that due to technology, the barriers to would be 'terrorists' of all kinds are falling and continue to fall. What this means is that despite the theatrics, the best, really the only way to prevent 'terrorism' is to create a global society that doesn't turn anybody into the kind of person who feels that such horrible things are permissible, or that 'the ends justify the means' in any way. Also, ambiguities in what society expects from people shouldn't be so great as to make every knowledge or power gradient 'game-able' like it is today.
Even if that greatly diminishes the profitability of raw capitalism.
Nobody should feel that they are so far above, entitled, or removed from society that they have any right to act in such a way.
But, people see such behavior every day, from the super-rich, for example. For whom a different justice system exists. They can do no wrong, while the poor - it seems in some peoples eyes, can do no right.
So, everything thats creates or permits a culture of impunity to exist, makes it harder and harder to prevent various forms of terrorism. Be it by state or non-state actors. Governments, the wealthy, and people who hold positions of advantage over others, like employers and people who hold public office or who have a fiduciary duty like legislators, bankers, lawyers, executors, and similar, especially should be held to much higher standards than anybody else when it comes to the areas they administer.
There are enough people out there who hate us that it wouldn't surprise me if there were occasional plots being foiled. Personally I suspect the various terrorist cells are taking a break to let things pan out, they already accomplished their goal with 9/11, we're still bleeding money, we're still suffering great inconvenience, we're still mired in multiple wars that have cost far more lives and money than the 9/11 attacks did and still have no exit plan. I said years ago that they're probably going to wait until we've spent all the money we're going to spend on fancy body scanners and such, wound down the wars and become complacent again, then they'll try something different to get everybody worked up again.
Follow the money.
Money is at the root of much evil.