You actually cannot stop it.
I am 51, and for all my life there have been nutjobs/freedom fighters/religious extremists (delete at will) trying it on.
The only ones you can stop are those prepared ,eventually. to accept that a political solution is the only way to stop the carnage. Which these islands reached with the IRA. (But stuff still occurs over there)
You cannot defeat terrorism. You cannot defeat a word. All you can do is minimise their impact, via intel mainly, and vigilance.
Any idiotic politician who spouts nonsense that he will end it, (Yes Trump, you, you absolute belter), whilst 1000s of his own "good old Mericans" keep seemingly happily gunning each other down, is deluded, at best. Down right dangerous more like.
Soz.