The worst attack in New Zealand's history has sparked a global pledge to fight violent content online. 51 people were killed in March when a gunman opened fire at two mosques in the city of Christchurch. The shooting was streamed live on Facebook, which was criticised for failing to stop the spread of the video. Two months on, New Zealand is leading what's being described as the "Christchurch Call" to combat hate speech and violent content on the internet. Social media firms and 18 governments have signed on. But the US is refusing to endorse it, saying the campaign threatens free speech. So, will this campaign work? Presenter: Folly Bah Thibault Guests: Eoin Lenihan - Researcher on Extremism online. Bjorn Ihler - Specialist on Countering Violent Extremism and a Survivor of the shooting attack in the Norwegian island of Utoya in 2011. Aral Balkan - Cyborg Rights Activist and author of the 'Ethical Design Manifesto'. - Subscribe to our channel: http://aje.io/AJSubscribe - Follow us on Twitter: https://twitter.com/AJEnglish - Find us on Facebook: https://www.facebook.com/aljazeera - Check our website: https://www.aljazeera.com/ #AlJazeeraEnglish #InsideStory #Christchurch