I was thoroughly in suspense throughout this magnificent film. I almost felt as if I was watching World War III unfurl like the Gulf War did on CNN, it was that convincing. Fonda as the President and Matthau as the Professor, in truly memorable performances, are superb in their roles and indeed the entire cast is strongly competent. Besides the unforgettable ending, by way of the President's unthinkable concession, are the arguments and attitudes of the Professor and Colonel Cascio. At the time it must have been very tempting to many hawks in Cold War administrations to end the deadlock whenever a seemingly decisive opening presented itself. I strongly recommend this film for its believablity and realism and even the final credits! 10/10.