Deterrence is not an “umbrella” protecting people from attack (“Weapons that are keeping the peace?”, leading article, 18 April). On the contrary, it is an activity by people sitting in submarines who are constantly ready and willing to murder millions of innocent people. And this activity is paid for out of our taxes. True, this wicked activity has so far helped to prevent war between the nuclear-armed states. But instead of recognising this, politicians in USA, Russia and Britain prefer to pretend that their bombs protect people in vulnerable states like the Baltics from nuclear threats which Putin cannot carry out. Pope Francis is right that nuclear disarmament is the only way out of this mess. Britain should begin it.Brian Wicker, Chairman, Pax Christi.The Scot