Kristensen is the director of the Nuclear Information Project with the Federation of American Scientists (FAS) in Washington, DC. His work focuses on researching and writing about the status of nuclear weapons and the policies that direct them. Kristensen is a co-author to the world nuclear forces overview in the SIPRI Yearbook (Oxford University Press) and a frequent adviser to the news media on nuclear weapons policy and operations. He has co-authored the Nuclear Notebook since 2001. Inquiries should be directed to FAS, 1112 16th Street NW, Suite 400, Washington, DC, 20036 USA; +1 (202) 546–3300.