At a time when the world is grappling with the twin threats of the pandemic and climate change, and the persistent threat of nuclear annihilation – all reminders of the urgency of global cooperation to overcome common challenges – the conflict in Ukraine is egregious and impossible to accept. The choices and decisions that leaders will make, particularly in relation to nuclear threats, will be a defining moment in history. It is not too late to place diplomacy at the forefront, for the voice of reason to prevail, and to wage peace and prevent the unnecessary loss of lives.