Two years ago, New Zealand’s Prime Minister Jacinda Ardern and France’s President Emmanuel Macron called together governments and tech companies to act to eliminate terrorist and violent extremist content online. The first Christchurch Call to Action summit was held in Paris in May 2019, two months after a gunman murdered 51 people at two mosques in Christchurch, New Zealand. The killer live-streamed his rampage for almost 17 minutes on Facebook, and the video was shared about 1.5 million times in 24 hours. Sixteen nations answered the Call, along with major internet companies, includi...