The 9/11 attacks 23 years ago make us see that borders are not always safe, and neither are people. The anonymity which terrorists enjoy makes it disconcerting to be around others on public transport like buses, planes, and trains. It isn’t easy to sit beside people we don’t know.
The likelihood of a terrorist attack is low but despite planning and action to stop it it’s also possible for some to still get through. It isn’t indiscriminate because terrorists pick targets. It’s part of their ingenuity to find gaps or loopholes in our thinking or security.
The trouble with the mind of a terrorist is that he’s ill already, and his actions are not met by his words. He says he hates, but so do many others. His intent is more ingrained in his way of life, his indoctrination, and his treatment. It takes a lot of ideas to make a man blow himself up.