Other people can tip you off to their plans, and you can arrest them with a backpack full of knives. That’s pretty reasonable suspicion that they were about to

Other people can tip you off to their plans, and you can arrest them with a backpack full of knives. That’s pretty reasonable suspicion that they were about to commit an act of terrorism. https://www.telegraph.co.uk/news/2017/04/27/armed-police-westminster-arrest-man-backpack-knives/ https://www.telegraph.co.uk/news/2017/04/27/armed-police-wes...