Stephen Herzog
@herzogsm.bsky.social
Professor of the Practice, James Martin Center for Nonproliferation Studies | Associate, Harvard Project on Managing the Atom | nuclear arms control, nonproliferation, disarmament, technology
3/5
Key takeaway 2:
Breakout is a race. Monitoring and verification remain ahead of proliferation-enabling emerging tech––for now. But accelerating commercial developments could shift that balance.
Key takeaway 2:
Breakout is a race. Monitoring and verification remain ahead of proliferation-enabling emerging tech––for now. But accelerating commercial developments could shift that balance.
December 1, 2025 at 3:00 PM
3/5
Key takeaway 2:
Breakout is a race. Monitoring and verification remain ahead of proliferation-enabling emerging tech––for now. But accelerating commercial developments could shift that balance.
Key takeaway 2:
Breakout is a race. Monitoring and verification remain ahead of proliferation-enabling emerging tech––for now. But accelerating commercial developments could shift that balance.
1/4
Policymakers often do listen to publics when formulating preferences on nuclear weapon use. Our #OpenAccess article provides first-of-kind evidence about when publics enable, constrain, or are less influential. @ejisbisa.bsky.social @cambup-polsci.cambridge.org
Link: doi.org/10.1017/eis....
Policymakers often do listen to publics when formulating preferences on nuclear weapon use. Our #OpenAccess article provides first-of-kind evidence about when publics enable, constrain, or are less influential. @ejisbisa.bsky.social @cambup-polsci.cambridge.org
Link: doi.org/10.1017/eis....
November 12, 2025 at 2:45 PM
1/4
Policymakers often do listen to publics when formulating preferences on nuclear weapon use. Our #OpenAccess article provides first-of-kind evidence about when publics enable, constrain, or are less influential. @ejisbisa.bsky.social @cambup-polsci.cambridge.org
Link: doi.org/10.1017/eis....
Policymakers often do listen to publics when formulating preferences on nuclear weapon use. Our #OpenAccess article provides first-of-kind evidence about when publics enable, constrain, or are less influential. @ejisbisa.bsky.social @cambup-polsci.cambridge.org
Link: doi.org/10.1017/eis....
I was a guest on the IISS podcast "The Arms Control Primer" w/ @bollfrass.bsky.social & former @iaeaorg.bsky.social DG Hans Blix. We covered some lessons of the Iraq case for nuclear nonproliferation & verification. Check out the new episode: www.iiss.org/podcasts/arm...
October 16, 2025 at 2:46 PM
I was a guest on the IISS podcast "The Arms Control Primer" w/ @bollfrass.bsky.social & former @iaeaorg.bsky.social DG Hans Blix. We covered some lessons of the Iraq case for nuclear nonproliferation & verification. Check out the new episode: www.iiss.org/podcasts/arm...
6/7
We find that early investments in advanced detection tech have big effects in offsetting the potential for AI-enhanced nuclear breakout.
We find that early investments in advanced detection tech have big effects in offsetting the potential for AI-enhanced nuclear breakout.
September 26, 2025 at 3:01 PM
6/7
We find that early investments in advanced detection tech have big effects in offsetting the potential for AI-enhanced nuclear breakout.
We find that early investments in advanced detection tech have big effects in offsetting the potential for AI-enhanced nuclear breakout.
4/7
Detection leads, but verification has historically evolved step-wise, often in response to crises. Commercially-driven dual-use technologies with WMD applications are currently evolving faster, with uncertain endpoints. Could we run into the situation depicted in this plot?
Detection leads, but verification has historically evolved step-wise, often in response to crises. Commercially-driven dual-use technologies with WMD applications are currently evolving faster, with uncertain endpoints. Could we run into the situation depicted in this plot?
September 26, 2025 at 3:01 PM
4/7
Detection leads, but verification has historically evolved step-wise, often in response to crises. Commercially-driven dual-use technologies with WMD applications are currently evolving faster, with uncertain endpoints. Could we run into the situation depicted in this plot?
Detection leads, but verification has historically evolved step-wise, often in response to crises. Commercially-driven dual-use technologies with WMD applications are currently evolving faster, with uncertain endpoints. Could we run into the situation depicted in this plot?
Atomic Backfires: When Nuclear Policies Fail is now available for pre-order from @mitpress.bsky.social! The thread below describes the premise of the volume and its contributors. mitpressbookstore.mit.edu/book/9780262...
September 17, 2025 at 9:09 AM
Atomic Backfires: When Nuclear Policies Fail is now available for pre-order from @mitpress.bsky.social! The thread below describes the premise of the volume and its contributors. mitpressbookstore.mit.edu/book/9780262...
Was delighted to be at KAIST yesterday for the U.S.-Korea International Workshop on Research Security and Integrity. We had very productive conversations about safeguarding research ecosystems against R&D misappropriation with incredibly welcoming and knowledgeable hosts!
September 5, 2025 at 1:36 PM
Was delighted to be at KAIST yesterday for the U.S.-Korea International Workshop on Research Security and Integrity. We had very productive conversations about safeguarding research ecosystems against R&D misappropriation with incredibly welcoming and knowledgeable hosts!
11/13
And there is a trade-off between verification success and costs, as the former asymptotically approaches 100% at increasingly greater expense but never quite gets there.
And there is a trade-off between verification success and costs, as the former asymptotically approaches 100% at increasingly greater expense but never quite gets there.
August 22, 2025 at 5:14 PM
11/13
And there is a trade-off between verification success and costs, as the former asymptotically approaches 100% at increasingly greater expense but never quite gets there.
And there is a trade-off between verification success and costs, as the former asymptotically approaches 100% at increasingly greater expense but never quite gets there.
6/13
Here are some of the international layers.
Here are some of the international layers.
August 22, 2025 at 5:14 PM
6/13
Here are some of the international layers.
Here are some of the international layers.
3/13
In the report, I therefore analyze a synthetic "worst-case" scenario: a hypothetical state that has the uranium enrichment program of Iran, the plutonium stockpile of Japan, and the weaponization knowledge of South Africa--simultaneously!
In the report, I therefore analyze a synthetic "worst-case" scenario: a hypothetical state that has the uranium enrichment program of Iran, the plutonium stockpile of Japan, and the weaponization knowledge of South Africa--simultaneously!
August 22, 2025 at 5:14 PM
3/13
In the report, I therefore analyze a synthetic "worst-case" scenario: a hypothetical state that has the uranium enrichment program of Iran, the plutonium stockpile of Japan, and the weaponization knowledge of South Africa--simultaneously!
In the report, I therefore analyze a synthetic "worst-case" scenario: a hypothetical state that has the uranium enrichment program of Iran, the plutonium stockpile of Japan, and the weaponization knowledge of South Africa--simultaneously!
2/13
Both advanced civilian nuclear powers and former nuclear-armed states present hurdles to irreversibility once the nuclear genie is out of the bottle.
Both advanced civilian nuclear powers and former nuclear-armed states present hurdles to irreversibility once the nuclear genie is out of the bottle.
August 22, 2025 at 5:14 PM
2/13
Both advanced civilian nuclear powers and former nuclear-armed states present hurdles to irreversibility once the nuclear genie is out of the bottle.
Both advanced civilian nuclear powers and former nuclear-armed states present hurdles to irreversibility once the nuclear genie is out of the bottle.
1/13
In a new report for @vertic.bsky.social, I take a hard look at the challenge that highly latent nuclear states present to irreversibility in nuclear disarmament. Summary and relevant tables and figures below. Read the report here: www.vertic.org/wp-content/u...
In a new report for @vertic.bsky.social, I take a hard look at the challenge that highly latent nuclear states present to irreversibility in nuclear disarmament. Summary and relevant tables and figures below. Read the report here: www.vertic.org/wp-content/u...
August 22, 2025 at 5:14 PM
1/13
In a new report for @vertic.bsky.social, I take a hard look at the challenge that highly latent nuclear states present to irreversibility in nuclear disarmament. Summary and relevant tables and figures below. Read the report here: www.vertic.org/wp-content/u...
In a new report for @vertic.bsky.social, I take a hard look at the challenge that highly latent nuclear states present to irreversibility in nuclear disarmament. Summary and relevant tables and figures below. Read the report here: www.vertic.org/wp-content/u...
Now out open access in the Journal of Conflict Resolution. @laurensukin.bsky.social, @lanoszka.bsky.social, & I investigate US reassurance efforts in 2023 during Russia's war on Ukraine.
We conducted public opinion surveys in 24 countries on 6 continents.
journals.sagepub.com/doi/10.1177/...
We conducted public opinion surveys in 24 countries on 6 continents.
journals.sagepub.com/doi/10.1177/...
August 14, 2025 at 4:45 PM
Now out open access in the Journal of Conflict Resolution. @laurensukin.bsky.social, @lanoszka.bsky.social, & I investigate US reassurance efforts in 2023 during Russia's war on Ukraine.
We conducted public opinion surveys in 24 countries on 6 continents.
journals.sagepub.com/doi/10.1177/...
We conducted public opinion surveys in 24 countries on 6 continents.
journals.sagepub.com/doi/10.1177/...
Was truly honored to share a room with such a knowledgeable, inspiring group at the Nobel Laureate Assembly for the Prevention of Nuclear War. The final declaration is a powerful, forward-looking call to action to reduce nuclear dangers: thebulletin.org/2025/07/the-...
July 17, 2025 at 1:09 PM
Was truly honored to share a room with such a knowledgeable, inspiring group at the Nobel Laureate Assembly for the Prevention of Nuclear War. The final declaration is a powerful, forward-looking call to action to reduce nuclear dangers: thebulletin.org/2025/07/the-...
2/8
Editors: me, @gdavidarceneaux.bsky.social, Ariel Petrovics.
Powerhouse contributors: Dave Allison, Tyler Bowen, @dbsalisbury.bsky.social, Binn Cho, Kristin Ven Bruusgaard, Sarah Bidgood, @jjjcameron.bsky.social, @professorrdg.bsky.social, Eliza Gheorghe, Ulrich Kühn, @laurensukin.bsky.social.
Editors: me, @gdavidarceneaux.bsky.social, Ariel Petrovics.
Powerhouse contributors: Dave Allison, Tyler Bowen, @dbsalisbury.bsky.social, Binn Cho, Kristin Ven Bruusgaard, Sarah Bidgood, @jjjcameron.bsky.social, @professorrdg.bsky.social, Eliza Gheorghe, Ulrich Kühn, @laurensukin.bsky.social.
July 3, 2025 at 2:48 PM
2/8
Editors: me, @gdavidarceneaux.bsky.social, Ariel Petrovics.
Powerhouse contributors: Dave Allison, Tyler Bowen, @dbsalisbury.bsky.social, Binn Cho, Kristin Ven Bruusgaard, Sarah Bidgood, @jjjcameron.bsky.social, @professorrdg.bsky.social, Eliza Gheorghe, Ulrich Kühn, @laurensukin.bsky.social.
Editors: me, @gdavidarceneaux.bsky.social, Ariel Petrovics.
Powerhouse contributors: Dave Allison, Tyler Bowen, @dbsalisbury.bsky.social, Binn Cho, Kristin Ven Bruusgaard, Sarah Bidgood, @jjjcameron.bsky.social, @professorrdg.bsky.social, Eliza Gheorghe, Ulrich Kühn, @laurensukin.bsky.social.
1/8
Later this year from @mitpress.bsky.social in @belfercenter.bsky.social's Studies in International Security book series-- Atomic Backfires: When Nuclear Policies Fail.
This is a sobering edited volume on how efforts to reduce nuclear weapons dangers may sometimes wind up exacerbating them.
Later this year from @mitpress.bsky.social in @belfercenter.bsky.social's Studies in International Security book series-- Atomic Backfires: When Nuclear Policies Fail.
This is a sobering edited volume on how efforts to reduce nuclear weapons dangers may sometimes wind up exacerbating them.
July 3, 2025 at 2:48 PM
1/8
Later this year from @mitpress.bsky.social in @belfercenter.bsky.social's Studies in International Security book series-- Atomic Backfires: When Nuclear Policies Fail.
This is a sobering edited volume on how efforts to reduce nuclear weapons dangers may sometimes wind up exacerbating them.
Later this year from @mitpress.bsky.social in @belfercenter.bsky.social's Studies in International Security book series-- Atomic Backfires: When Nuclear Policies Fail.
This is a sobering edited volume on how efforts to reduce nuclear weapons dangers may sometimes wind up exacerbating them.
It was wonderful to have some very, very late night sunlight up north in Swedish Lapland, in-between the Annual Conference at the Alva Myrdal Center for Nuclear Disarmament @uupeace.bsky.social and a nuclear-AI dialogue at @sipri.org.
June 23, 2025 at 3:59 PM
It was wonderful to have some very, very late night sunlight up north in Swedish Lapland, in-between the Annual Conference at the Alva Myrdal Center for Nuclear Disarmament @uupeace.bsky.social and a nuclear-AI dialogue at @sipri.org.