The Half-Lives of Others is a comparative historical study of how intelligence agencies perform in assessing the proliferation potential of foreign nuclear programs. Contrary to pervasive skepticism, the study finds that intelligence agencies are generally adept at proliferation assessment and more likely to underestimate proliferation risks than to inflate them. Errors arise systematically from characteristics of the assessed programs and the assessment process itself. Nuclear programs that do not have international safeguards, include an advanced infrastructure, and import key technologies pose a special challenge to intelligence assessors. Countries holding open debates about their nuclear options and those who do not make formal nonproliferation commitments will also be difficult to assess. Using original archival and declassified documents, the study arrives at these conclusions by measuring the accuracy of American, British, East German, and several other European intelligence estimates, with a special focus on their assessments of the West German, Chinese, Indian, Argentine, and Pakistani programs.

Alexander K. Bollfrass is a Stanton Nuclear Security Postdoctoral Fellow at Harvard Kennedy School's Belfer Center, specializing in nuclear weapons policy and proliferation. His research compares how well intelligence agencies perform in assessing other countries' nuclear programs. Its main focus is on the foreign intelligence branch of the Stasi, the former East German intelligence service. In parallel, Bollfrass pursues research interests on how climate affects civil wars and the ethical dilemmas of serving the security state. He was a nuclear weapons policy researcher at the Washington-based Stimson Center and Arms Control Association before earning a Ph.D. in security studies from Princeton University's Woodrow Wilson School of Public and International Affairs. Bollfrass also holds an undergraduate degree in political science from the University of California, Berkeley.