James Acton
@nuclear-jim.bsky.social
Co-director of the Nuclear Policy Program at the Carnegie Endowment For International Peace. I spend a lot of time thinking about nuclear weapons, advanced nonnuclear technology, and escalation.
Reposted by James Acton
Testing nuclear weapons by detonating warheads is like “nuking yourself in the foot,” writes @nuclear-jim.bsky.social. Trump can stop nuclear anarchy by testing in ways that don’t spark a global arms race or give away the U.S.’s data advantage.
More here: carnegieendowment.org/emissary/202...
More here: carnegieendowment.org/emissary/202...
Trump Has an Out on Nuclear Testing. He Should Take It.
Sometimes good policy can be as simple as not nuking yourself in the foot.
carnegieendowment.org
November 6, 2025 at 6:39 PM
Testing nuclear weapons by detonating warheads is like “nuking yourself in the foot,” writes @nuclear-jim.bsky.social. Trump can stop nuclear anarchy by testing in ways that don’t spark a global arms race or give away the U.S.’s data advantage.
More here: carnegieendowment.org/emissary/202...
More here: carnegieendowment.org/emissary/202...
Let's not nuke ourselves in the foot!
I explain why it's so difficult to know if China and Russia are conducting ultra-low yield tests and why, even if they are, it's not in U.S. interests to restart testing. @carnegieendowment.org @carnegienpp.bsky.social
carnegieendowment.org/emissary/202...
I explain why it's so difficult to know if China and Russia are conducting ultra-low yield tests and why, even if they are, it's not in U.S. interests to restart testing. @carnegieendowment.org @carnegienpp.bsky.social
carnegieendowment.org/emissary/202...
Trump Has an Out on Nuclear Testing. He Should Take It.
Sometimes good policy can be as simple as not nuking yourself in the foot.
carnegieendowment.org
November 6, 2025 at 5:11 PM
Let's not nuke ourselves in the foot!
I explain why it's so difficult to know if China and Russia are conducting ultra-low yield tests and why, even if they are, it's not in U.S. interests to restart testing. @carnegieendowment.org @carnegienpp.bsky.social
carnegieendowment.org/emissary/202...
I explain why it's so difficult to know if China and Russia are conducting ultra-low yield tests and why, even if they are, it's not in U.S. interests to restart testing. @carnegieendowment.org @carnegienpp.bsky.social
carnegieendowment.org/emissary/202...
I am entirely indifferent whether, in the event of a nuclear war, I am incinerated by a nuclear warhead delivered by a "traditional" ICBM, a hypersonic glider, a nuclear-powered cruise missile, or a nuclear-powered torpedo.
All seem equally suboptimal to me.
All seem equally suboptimal to me.
elmo from sesame street standing in front of a wall
ALT: elmo from sesame street standing in front of a wall
media.tenor.com
November 5, 2025 at 3:29 PM
I am entirely indifferent whether, in the event of a nuclear war, I am incinerated by a nuclear warhead delivered by a "traditional" ICBM, a hypersonic glider, a nuclear-powered cruise missile, or a nuclear-powered torpedo.
All seem equally suboptimal to me.
All seem equally suboptimal to me.
The End of MAD?
Join me, Steve Fetter, @jaysankarans.bsky.social, TD MacDonald, Ton Stefanik, @lauraegrego.bsky.social, @fiona-cunningham.bsky.social, and Charlie Glaser to discuss whether technological developments are undermining mutually assured destruction.
Link for virtual rego in next post.
Join me, Steve Fetter, @jaysankarans.bsky.social, TD MacDonald, Ton Stefanik, @lauraegrego.bsky.social, @fiona-cunningham.bsky.social, and Charlie Glaser to discuss whether technological developments are undermining mutually assured destruction.
Link for virtual rego in next post.
a man in a shirt and tie is screaming with his hands in the air .
ALT: a man in a shirt and tie is screaming with his hands in the air .
media.tenor.com
September 30, 2025 at 1:47 PM
The End of MAD?
Join me, Steve Fetter, @jaysankarans.bsky.social, TD MacDonald, Ton Stefanik, @lauraegrego.bsky.social, @fiona-cunningham.bsky.social, and Charlie Glaser to discuss whether technological developments are undermining mutually assured destruction.
Link for virtual rego in next post.
Join me, Steve Fetter, @jaysankarans.bsky.social, TD MacDonald, Ton Stefanik, @lauraegrego.bsky.social, @fiona-cunningham.bsky.social, and Charlie Glaser to discuss whether technological developments are undermining mutually assured destruction.
Link for virtual rego in next post.
Reposted by James Acton
What exactly is the government hiding in Tucson? Not much, says @nuclear-jim.bsky.social. He got an interesting souvenir there, regardless.
See the first installment of Carnegie Office Hours for more treasures from James (if not nuclear secrets) here: buff.ly/dlUzF6n
See the first installment of Carnegie Office Hours for more treasures from James (if not nuclear secrets) here: buff.ly/dlUzF6n
August 13, 2025 at 2:12 PM
What exactly is the government hiding in Tucson? Not much, says @nuclear-jim.bsky.social. He got an interesting souvenir there, regardless.
See the first installment of Carnegie Office Hours for more treasures from James (if not nuclear secrets) here: buff.ly/dlUzF6n
See the first installment of Carnegie Office Hours for more treasures from James (if not nuclear secrets) here: buff.ly/dlUzF6n
I feel pretty strongly the @nytimes.com has the wrong framing here. This isn't serious; it's pathetic.
I'd suggest something like:
"Trump throws social media hissy fit invoking nukes after public spat with ex-president of Russia."
I'd suggest something like:
"Trump throws social media hissy fit invoking nukes after public spat with ex-president of Russia."
August 1, 2025 at 6:56 PM
I feel pretty strongly the @nytimes.com has the wrong framing here. This isn't serious; it's pathetic.
I'd suggest something like:
"Trump throws social media hissy fit invoking nukes after public spat with ex-president of Russia."
I'd suggest something like:
"Trump throws social media hissy fit invoking nukes after public spat with ex-president of Russia."
As much as I deplore nuclear signaling by tweet--can't believe I just wrote that--I would NOT necessarily assume there's a been change to the US nuclear posture. The U.S. always keeps ~4/5 SSBNs at sea ready to fire.
August 1, 2025 at 5:50 PM
As much as I deplore nuclear signaling by tweet--can't believe I just wrote that--I would NOT necessarily assume there's a been change to the US nuclear posture. The U.S. always keeps ~4/5 SSBNs at sea ready to fire.
Ahem
(Deleted earlier version, which was missing caption!)
(Deleted earlier version, which was missing caption!)
August 1, 2025 at 5:42 PM
Ahem
(Deleted earlier version, which was missing caption!)
(Deleted earlier version, which was missing caption!)
Ah, yes, that crucial ninth significant figure...
July 31, 2025 at 3:29 PM
Ah, yes, that crucial ninth significant figure...
Good gracious, Ignatius!
Why I disagree with the normally excellent David Ignatius; recent oped on Iran.
Why I disagree with the normally excellent David Ignatius; recent oped on Iran.
Ignatius's oped is written as if it's a news story. The "news" in this case is that--SURPRISE!--an Israeli source backed up claims by the Israeli government! (3/n)
x.com/james_acton3...
x.com/james_acton3...
July 29, 2025 at 2:59 PM
Good gracious, Ignatius!
Why I disagree with the normally excellent David Ignatius; recent oped on Iran.
Why I disagree with the normally excellent David Ignatius; recent oped on Iran.
The case for attacking Iran relied on emphasizing its technical prowess.
The case that strikes were successful requires claiming that Iran is technically incompetent.
foreignpolicy.com/2025/07/25/i...
The case that strikes were successful requires claiming that Iran is technically incompetent.
foreignpolicy.com/2025/07/25/i...
There’s More Than One Way to Build a Bomb
Iran doesn’t need to rebuild its damaged facilities to sprint for a nuclear weapon.
foreignpolicy.com
July 29, 2025 at 2:56 PM
The case for attacking Iran relied on emphasizing its technical prowess.
The case that strikes were successful requires claiming that Iran is technically incompetent.
foreignpolicy.com/2025/07/25/i...
The case that strikes were successful requires claiming that Iran is technically incompetent.
foreignpolicy.com/2025/07/25/i...
On Friday, I argued in @foreignpolicy.com that Trump admin claims it had set Iran back by "years" were true but disingenuous.
The same day, the normally excellent David Ignatius amplified the misleading U.S. and Israeli narrative.
www.washingtonpost.com/opinions/202...
Let's take a look... (1/n)
The same day, the normally excellent David Ignatius amplified the misleading U.S. and Israeli narrative.
www.washingtonpost.com/opinions/202...
Let's take a look... (1/n)
Opinion | The 12 days that turned back the clock on Iran’s nuclear program
Israeli and American assessments agree Tehran’s infrastructure to finish a bomb is shattered.
www.washingtonpost.com
July 28, 2025 at 2:42 PM
On Friday, I argued in @foreignpolicy.com that Trump admin claims it had set Iran back by "years" were true but disingenuous.
The same day, the normally excellent David Ignatius amplified the misleading U.S. and Israeli narrative.
www.washingtonpost.com/opinions/202...
Let's take a look... (1/n)
The same day, the normally excellent David Ignatius amplified the misleading U.S. and Israeli narrative.
www.washingtonpost.com/opinions/202...
Let's take a look... (1/n)
🎶When you attend a funeral,
It is sad to think that sooner orl…
…ater, those you love will do the same for you.
And you may have found it tragic,
Not to mention other adjec..
…tives to think of all the weeping they will do. 🎶
RIP, Mr Lehrer.
It is sad to think that sooner orl…
…ater, those you love will do the same for you.
And you may have found it tragic,
Not to mention other adjec..
…tives to think of all the weeping they will do. 🎶
RIP, Mr Lehrer.
My last living musical hero is still my hero but unfortunately no longer living. RIP to the great, great Mr. Tom Lehrer.
July 27, 2025 at 6:20 PM
🎶When you attend a funeral,
It is sad to think that sooner orl…
…ater, those you love will do the same for you.
And you may have found it tragic,
Not to mention other adjec..
…tives to think of all the weeping they will do. 🎶
RIP, Mr Lehrer.
It is sad to think that sooner orl…
…ater, those you love will do the same for you.
And you may have found it tragic,
Not to mention other adjec..
…tives to think of all the weeping they will do. 🎶
RIP, Mr Lehrer.
Me in @foreignpolicy.com.
The Trump administration's claim that Iran would need "years" to rebuild its previous nuclear program is like asserting that an unlocked bank vault would be impervious to a cyberattack.
It’s true but misses the point.
foreignpolicy.com/2025/07/25/i...
The Trump administration's claim that Iran would need "years" to rebuild its previous nuclear program is like asserting that an unlocked bank vault would be impervious to a cyberattack.
It’s true but misses the point.
foreignpolicy.com/2025/07/25/i...
There’s More Than One Way to Build a Bomb
Iran doesn’t need to rebuild its damaged facilities to sprint for a nuclear weapon.
foreignpolicy.com
July 25, 2025 at 3:28 PM
Me in @foreignpolicy.com.
The Trump administration's claim that Iran would need "years" to rebuild its previous nuclear program is like asserting that an unlocked bank vault would be impervious to a cyberattack.
It’s true but misses the point.
foreignpolicy.com/2025/07/25/i...
The Trump administration's claim that Iran would need "years" to rebuild its previous nuclear program is like asserting that an unlocked bank vault would be impervious to a cyberattack.
It’s true but misses the point.
foreignpolicy.com/2025/07/25/i...
Reposted by James Acton
had @nuclear-jim.bsky.social on Angry Planet to explain what the current nuclear arm's race looks like. It's bad!
He's got a solution that sounds radical, but is more palatable than living in a world where everyone is spending billions to construct more nukes
He's got a solution that sounds radical, but is more palatable than living in a world where everyone is spending billions to construct more nukes
How Many Nukes Does It Take to Win a War? (Trick Question)
The world is living with a Cold War hangover.
angryplanetpod.com
July 24, 2025 at 6:35 PM
had @nuclear-jim.bsky.social on Angry Planet to explain what the current nuclear arm's race looks like. It's bad!
He's got a solution that sounds radical, but is more palatable than living in a world where everyone is spending billions to construct more nukes
He's got a solution that sounds radical, but is more palatable than living in a world where everyone is spending billions to construct more nukes
🧵How much damage was done to Iran's nuclear program?
An analysis of Friday's reporting of the U.S. government assessment. I'll focus on the @nytimes.com, which was clearer than the earlier but confused @nbcnews.com story. (1/n)
www.nytimes.com/2025/07/17/u...
An analysis of Friday's reporting of the U.S. government assessment. I'll focus on the @nytimes.com, which was clearer than the earlier but confused @nbcnews.com story. (1/n)
www.nytimes.com/2025/07/17/u...
New Assessment Finds Site at Focus of U.S. Strikes in Iran Badly Damaged
www.nytimes.com
July 21, 2025 at 2:09 PM
🧵How much damage was done to Iran's nuclear program?
An analysis of Friday's reporting of the U.S. government assessment. I'll focus on the @nytimes.com, which was clearer than the earlier but confused @nbcnews.com story. (1/n)
www.nytimes.com/2025/07/17/u...
An analysis of Friday's reporting of the U.S. government assessment. I'll focus on the @nytimes.com, which was clearer than the earlier but confused @nbcnews.com story. (1/n)
www.nytimes.com/2025/07/17/u...
I can think of no reason at all why Iranian leaders won’t jump at the chance to follow the “Libya model.”
Can you, Muammar?
Can you, Muammar?
July 11, 2025 at 3:14 PM
I can think of no reason at all why Iranian leaders won’t jump at the chance to follow the “Libya model.”
Can you, Muammar?
Can you, Muammar?
Reposted by James Acton
Important piece from @nuclear-jim.bsky.social about how to develop a better nuclear deterrence posture. www.cfr.org/report/optim... James’ deep thinking on these matters is desperately needed at a time when deterrence debate at times sounds more like Cold War grab-bag posturing on autopilot.
Optimal Deterrence
The United States faces growing dangers of nuclear escalation, a new arms race, and proliferation. This report recommends an improved strategy for “optimal deterrence” and a path to rebuilding relati…
www.cfr.org
July 11, 2025 at 12:51 PM
Important piece from @nuclear-jim.bsky.social about how to develop a better nuclear deterrence posture. www.cfr.org/report/optim... James’ deep thinking on these matters is desperately needed at a time when deterrence debate at times sounds more like Cold War grab-bag posturing on autopilot.
Personally, I'm open to all three possibilities--that all, some, or none of the HEU was moved pre-war. I simply don't know and there appears to be real disagreement among intel agencies here.
Is the assessment that the HEU has not been removed before the strikes now the commonly accepted view? And if so, isn't it better if the HEU is maybe not completely buried than if it had been moved to unknown sites?
www.timesofisrael.com/senior-israe...
www.timesofisrael.com/senior-israe...
Senior Israeli official: Intel shows enriched uranium was at Iran sites when bombed
Official says Isfahan stockpile may still be accessible, but with difficulty; Netanyahu says Israel ‘didn’t deal with’ Iran’s enriched uranium during war: 'We think we know where it is'
www.timesofisrael.com
July 10, 2025 at 6:55 PM
Personally, I'm open to all three possibilities--that all, some, or none of the HEU was moved pre-war. I simply don't know and there appears to be real disagreement among intel agencies here.
It'd be a pretty catastrophic outcome *IF* the attacks on Fordow failed to destroy centrifuges and they can be put back into service. I'm not claiming this is the case, but U.S. officials seem to be hinting it's a possibility. (1/n)
@hugolowell.bsky.social
@hugolowell.bsky.social
July 10, 2025 at 6:43 PM
It'd be a pretty catastrophic outcome *IF* the attacks on Fordow failed to destroy centrifuges and they can be put back into service. I'm not claiming this is the case, but U.S. officials seem to be hinting it's a possibility. (1/n)
@hugolowell.bsky.social
@hugolowell.bsky.social
lol
And you just lost the nuclear war, using Colin Gray’s terminology, the enemy will have enough (~50y) time to recover, you will never fully recover o the pre-war period.
CMI is dangerous nonsense.
5/5
CMI is dangerous nonsense.
5/5
July 9, 2025 at 9:59 PM
lol
🧵Introducing optimal deterrence.
Here's my proposed U.S. nuclear strategy for managing escalation, arms racing, and proliferation with two nuclear peers, published through @cfr.org.
Health warning: If you like counterforce, take a DEEP breath before reading on. (1/n)
www.cfr.org/report/optim...
Here's my proposed U.S. nuclear strategy for managing escalation, arms racing, and proliferation with two nuclear peers, published through @cfr.org.
Health warning: If you like counterforce, take a DEEP breath before reading on. (1/n)
www.cfr.org/report/optim...
Optimal Deterrence
The United States faces growing dangers of nuclear escalation, a new arms race, and proliferation. This report recommends an improved strategy for “optimal deterrence” and a path to rebuilding relati…
www.cfr.org
July 9, 2025 at 2:37 PM
🧵Introducing optimal deterrence.
Here's my proposed U.S. nuclear strategy for managing escalation, arms racing, and proliferation with two nuclear peers, published through @cfr.org.
Health warning: If you like counterforce, take a DEEP breath before reading on. (1/n)
www.cfr.org/report/optim...
Here's my proposed U.S. nuclear strategy for managing escalation, arms racing, and proliferation with two nuclear peers, published through @cfr.org.
Health warning: If you like counterforce, take a DEEP breath before reading on. (1/n)
www.cfr.org/report/optim...
Reposted by James Acton
"It always seemed to me that [diplomacy] was a much more promising avenue than military action, which has only modestly eroded Iran’s capability to build the bomb, while increasing its incentives to do so.” @nuclear-jim.bsky.social @newstatesman.com on Iran: www.newstatesman.com/internationa...
The hunt for Iran’s missing uranium
Somewhere in the country, enough material to make ten nuclear bombs remains hidden.
www.newstatesman.com
July 4, 2025 at 10:18 AM
"It always seemed to me that [diplomacy] was a much more promising avenue than military action, which has only modestly eroded Iran’s capability to build the bomb, while increasing its incentives to do so.” @nuclear-jim.bsky.social @newstatesman.com on Iran: www.newstatesman.com/internationa...
My friend, Joshua Pollack, penned this beautiful and wry double obituary of his father, Jonathan Pollack, and his first boss, Barry Blechman.
www.armscontrolwonk.com/archive/1220...
www.armscontrolwonk.com/archive/1220...
Recalling two mentors
1. Jonathan D. Pollack My father, Jonathan Pollack, died at the end of May after what’s politely called a long convalescence. He had worked over several [...]
www.armscontrolwonk.com
July 2, 2025 at 8:26 PM
My friend, Joshua Pollack, penned this beautiful and wry double obituary of his father, Jonathan Pollack, and his first boss, Barry Blechman.
www.armscontrolwonk.com/archive/1220...
www.armscontrolwonk.com/archive/1220...