Trees, bushes, swales, ponds, are all effective barriers. Besides, terror attacks are a tiny, tiny, nearly insignificant percentage of human behavior.

If not sensationalized, they would be non-events in the grand scheme of life. We have over 7 billion people going about their business every day. We have deranged kooks who want to kill themselves and some others, what, 10-20 times per year?

Daily, 150 thousand people die from one thing or another. Terrorism is a non-starter except for politicians and the arms industry. Spend the money on making things better for life and terrorism will evaporate. Green it up!