Lines of code (plus training data) are already writing university-level essays, creating images indistinguishable from art and photos, passing exams, beating the world's best board and strategy game players, making chart-topping music, designing drugs, folding proteins and more. It's not at all a stretch of the imagination that they will fairly soon be able to tell people how to modify viruses to make them more infectious or more deadly, figure out how to design nuclear weapons, and discover new weapons of mass destruction that will be much cheaper and easier to make.