President Obama will seek cuts with Russia of up to one-third of nuclear weapons Writers: No such thing as “acceptable” level; even lesser amount could obliterate humanity Writers: 300 warheads would kill 100 million; the rest would die from starvation, poisoning We cannot maintain nuclear arsenals indefinitely and still avoid a nuclear war, they say Editor’s note: Ira Helfand is a past president of Physicians for Social Responsibility and co-president of the International Physicians for the Prevention of Nuclear War. Alan Robock is a distinguished professor of climate science at Rutgers University and a fellow of the American Meteorological Society, American Geophysical Union and American Association for the Advancement of Science.