A new debate on tactical nuclear weapons in Europe has now begun. These two sharply contrasting books represent its outer limits. Cohen, the acknowledged "father of the neutron bomb," and Van Cleave, a member of the "B" team in the CIA's competitive intelligence analysis of 1976, criticize NATO's emphasis on a conventional defense and question the credibility under present circumstances of the "coupling" of Europe's security to the U.S. strategic force. They call for a substantial modernization of NATO's nuclear posture through miniaturization and improved accuracy so as to provide a stronger war-fighting capability. The SIPRI volume, although containing a spread of views (including a short piece by the Soviet expert, M. Milshtein), points in the opposite direction. The risks that new tactical weapons may make a nuclear war more likely are emphasized. Imaginative ideas for arms control are put forth, although the contributions are somewhat uneven. Neither book, however, has the sophistication which will be needed to make sound judgments in the emerging debate.