Lachlan MacKenzie

Research Associate, Project on Nuclear Issues
Lachlan MacKenzie

Lachlan MacKenzie is a research associate with the Project on Nuclear Issues in the Defense and Security Department at the Center for Strategic and International Studies (CSIS). His research focuses on Russian nuclear signaling, two-peer competition, and nuclear modernization. Previously, he interned with the Institute for the Study of War and the Institute for National Strategic Studies. He earned a BA in international relations from Brown University, where he graduated with honors. His thesis explored Russia's motivations for developing novel nuclear delivery systems.

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Russia’s Latest Nuclear Saber-Rattling: Nuclear Testing?

President Putin’s instruction for Russian military and political leaders to begin “preparations for nuclear weapons tests” follows President Trump’s similar order last week, but also fits a wider pattern of nuclear saber-rattling tied to the ongoing war in Ukraine.

Critical Questions by Heather Williams and Lachlan MacKenzie — November 5, 2025

Audio Briefs

Ukraine’s Drone Swarms Are Destroying Russian Nuclear Bombers. What Happens Now?

An audio version of “⁠Ukraine’s Drone Swarms Are Destroying Russian Nuclear Bombers. What Happens Now?⁠,” a new Critical Questions by CSIS's Masao Dahlgren and Lachlan MacKenzie. This audio was generated with text-to-speech by Eleven Labs. 

Podcast Episode by Masao Dahlgren and Lachlan MacKenzie — June 4, 2025

Audio Briefs

Game On: Opportunities for Euro-Atlantic Strategic Stability and Arms Control

Europe is likely to remain a theater of instability despite pressure for a peace settlement in Ukraine. As the United States shifts toward the Indo-Pacific and Russia continues to pursue its territorial ambitions, what might arms control look like after the war in Ukraine?

Report by Heather Williams, Nicholas Adamopoulos, Lachlan MacKenzie, and Catherine Murphy — April 21, 2025

Why Does the United States Need a More Flexible Nuclear Force?

Deterrence is emerging as a theme for Secretary of Defense Pete Hegseth, but questions remain about the Trump administration’s ability to deliver and maintain the nation’s nuclear deterrent.

Critical Questions by Heather Williams and Lachlan MacKenzie — April 3, 2025

Audio Briefs

Why Does the United States Need a More Flexible Nuclear Force?

An audio version of “Why Does the United States Need a More Flexible Nuclear Force?,” a new Critical Questions by CSIS's Heather Williams and Lachlan MacKenzie. This audio was generated with text-to-speech by Eleven Labs.

Podcast Episode by Heather Williams and Lachlan MacKenzie — April 3, 2025

Audio Briefs

Report Launch: Project Atom 2024

Please join the CSIS Project on Nuclear Issues (PONI) on Wednesday, November 20, 2024 at 9:00 am ET, for the launch of its report, Project Atom 2024. 

Event — November 20, 2024

Project Atom 2024: Intra-War Deterrence in a Two-Peer Environment

There is a growing risk that U.S. adversaries might resort to nuclear use in a regional conflict. To help address for this threat, the Project on Nuclear Issues invited a group of experts to develop competing strategies for responding to strategic deterrence failure.

Report by Heather Williams, Reja Younis, Lachlan MacKenzie, Christopher A. Ford, Rebecca Davis Gibbons, Ankit Panda, Melanie W. Sisson, and Gregory Weaver — November 18, 2024