Calder Walton is Assistant Director of the Belfer Center's Applied History Project and Intelligence Project. He is one of the world's leading experts on the history of intelligence, national security, and geopolitics. His research, and commentary, about global security frequently appear in major news and broadcast outlets on both sides of the Atlantic.

Calder’s latest book, Spies. The Epic Intelligence War between East and West (2023), is a best-selling exposé of the history of Russian intelligence. Described as "riveting" by the Economist and "a masterpiece" by University of Cambridge History Professor Emeritus Christopher Andrew, it reveals that, contrary to what many in the West thought, the Cold War did not end with the Soviet Union's collapse in 1991, but in fact continued after. Today, Western governments are in a new Cold War with Russia and China, with intelligence agencies once again at the frontline.

His work has been published and featured in Foreign Affairs, Foreign Policy, CNN, Time Magazine, The New York Times, The Washington Post, The Sunday Times, POLITICO, Newsweek, Prospect Magazine, the BBC, NPR, PBS, C-SPAN, FOX News, News Nation, and academic peer reviewed journals such as Intelligence & National Security and the Texas National Security Review.

Calder is also general editor of the multi-volume Cambridge History of Espionage and Intelligence to be published by Cambridge University Press. Over three volumes, with ninety chapters by leading scholars, this project will be a landmark study of intelligence, exploring its use and abuse in statecraft and warfare from the ancient world to the present day.

Calder's research builds on his first (award-winning) book, Empire of Secrets. British Intelligence, the Cold War and the Twilight of Empire (2013). While pursuing a doctorate in History at Trinity College, Cambridge, England, and then a Junior Research Fellowship also at Cambridge University, he was a lead researcher on Professor Christopher Andrew's unprecedented official history of the British Security Service (MI5), Defend the Realm (2009). This research position gave Calder, for six years, privileged access to the archives of MI5, the world's longest continuous-running security intelligence agency.

As well as his research on intelligence history, Calder is also an English-qualified Barrister (attorney). He lives in Cambridge, Massachusetts, with his wife and son, who teaches him more about skulduggery than anything else. 

For speaking engagements for Calder, please contact Ellis Trevor:

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