They do not work in industries associated with the military, do not serve in the armed services, and refuse national military service, which in some countries may result in their arrest and imprisonment. They do not salute or pledge allegiance to flags or sing national anthems or patriotic songs. Jehovah's Witnesses see themselves as a worldwide brotherhood that transcends national boundaries and ethnic loyalties. Sociologist Ronald Lawson has suggested the religion's intellectual and organizational isolation, coupled with the intense indoctrination of adherents, rigid internal discipline and considerable persecution, has contributed to the consistency of its sense of urgency in its apocalyptic message.