Propaganda is a common element in many, if not all, terrorist incidents. Objectives are usually to instil fear in the target population but may also include winning approval from associates and inspiring new adherents. The advent of social media has greatly expanded opportunities for achieving these objectives. The attacks on worshipers in two mosques in Christchurch, New Zealand, on 15 March 2019 resulting in the murder of 51 people and the live streaming of the attack on Facebook were met with responses from governments in New Zealand, France and Australia that sought international cooperation in finding effective counter-measures to the propaganda value of the attacks. Australia’s ambitious regulatory approach is problematic when considered in an international context particularly in relation to the need to take account of free speech guarantees. However, since it recognises the need for international solutions in this area, there are opportunities to explore other ways of achieving its objectives.