IRA HELFAND and ROBERT DODGE – As physicians we spend our professional lives applying scientific facts to the health and well being of our patients. When it comes to public health threats like TB, polio, cholera, AIDS and others where there is no cure, our aim is to prevent what we cannot cure. It is our professional, ethical and moral obligation to educate and speak out on these issues. That said, the greatest imminent existential threat to human survival is potential of global nuclear war.