Atrocity crimes are unfolding with impunity in Gaza, Sudan and Myanmar. For Mô Bleeker, the UN Secretary-General’s Special Advisor on the Responsibility to Protect, the task has never felt more urgent – or more difficult. “Even when it’s very hard, you have to go on. We are living in a very critical moment.” Sitting by Lake Neuchâtel near her home in Switzerland, Mô Bleeker, the UN Secretary-General’s Special Advisor on the Responsibility to Protect, reflects on a turning point in global governance that marked a “very important normative shift”, meant to build a world less defined by conflict and cruelty. Twenty years ago, all UN heads of state and government endorsed the Responsibility to Protect. The commitment redefined sovereignty – once understood mainly as a right of non-interference – as a duty to protect populations and prevent atrocity crimes. These include genocide, war crimes, ethnic cleansing and crimes against humanity. Today, that principle is at the heart of her work.