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Sipping coffee on a winter break morning, David Kearn of St. John's University scanned through his day's list of memos and reports when a new paper caught his eye.
"The role of nuclear weapons in a Taiwan crisis," read its title.
Published by the Atlantic Council in late November, the report discussed how a potential US-China war over Taiwan might play out — and how the Pentagon might win with tactical nuclear bombs.
Kearn was stunned. This was coming from a serious analyst for an organization of repute.
"I mean, geez," the associate professor of government and politics told Business Insider. "This really seems like a radical departure even for the defense think tank world."
In his 20 years of researching nuclear arms — including a post at RAND and advising the US Defense Secretary's office — he'd never seen such overt posturing about nukes against China.
The paper's author, Greg Weaver, is influential and experienced. A former deputy director of the Joint Chiefs of Staff, Weaver was also principal director for US nuclear and missile defense policy at the Defense Department during the Obama years.
One possible nuclear target, his paper wrote, might be Chinese ground troops sailing across the Taiwan Strait.
A week later, the Atlantic Council published a separate, similar paper by political scientist Matthew Kroenig. He was one of 12 experts appointed by Congress to advise US nuclear strategy. His report's title began: "Deliberate nuclear use in a war over Taiwan."
Neither author outright argued for a first-strike nuclear attack on China. But they asked the US to seriously consider the option for a Taiwan war, largely as a deterrent — and to let Beijing know it's on the table.
Alarmed, several US nuclear scholars rushed to criticize the papers, including Kearn, who slammed them as "strategic myopia" in a scathing commentary.
Months later, the November reports still rest uneasily with top academics, who see the papers as inflammatory fringe rhetoric that's leaping to the fore in the US. But Kroenig and Weaver's arguments have been met with approval from other respected figures in nuclear scholarship, who say the outrage is unwarranted.
Their debate underscores a deeper shift among leading US minds toward a starkly more aggressive nuclear posture against China, which the US says will become a rival nuclear superpower by 2035 but has refused to take part in crucial talks so far.
Business Insider spoke to nine nuclear arms scholars and US-China relations experts about the November reports and their implications on two countries so entangled in their economies and influence.
"Now that China is becoming conventionally powerful, the US threats of nuclear first-use are moving further to the forefront," said James Acton, co-director of the Nuclear Policy Program at the Carnegie Endowment for International Peace.
"My sense is that what Greg and Matt were writing is very much a reflection of what already goes on within the US military," he added.
To be sure, US nuclear policy doesn't rule out first strikes. But scholars who disagree with Kroenig and Weaver, several of whom work closely with experts in China, warned against the idea of making a threat.
"It's a dangerous line of thinking, and it's extremely reckless," said Lyle Goldstein, director of the China Initiative at Brown University.
He said such threats would only escalate tensions, not shock China into backing off from Taiwan as Kroenig and Weaver might hope.
Beijing has known for decades that the Pentagon may launch a nuclear first strike, said Goldstein. The US once floated nuclear retaliation in 1958 if China invaded Taiwan, and stationed nuclear weapons on the island until 1974.
When Goldstein visited China in early 2023, local experts reiterated to him that the country sees Washington as growing extremely aggressive, and still actively discusses how the US may launch a nuclear strike.
"Maybe Kroenig is right. Maybe China will say: 'OK, we don't want nuclear war, forget this whole thing, we're not interested in Taiwan at all.' But I don't think so at all," Goldstein said. "In fact, I think the opposite will happen."
Acton of the Carnegie Endowment for International Peace also disagreed that the US should emphasize its strike capabilities.
"China already thinks this. Chinese experts write a lot about how they think the US sees the nuclear threshold as being very low," he said.
Francesca Giovannini, executive director of the Project on Managing the Atom at Harvard University's Kennedy School, fears all sides are losing clarity on the mutual boundaries that prevent a large-scale nuclear war.
"In China, it is obvious in their minds that the US now treats Taiwan as it would treat South Korea or Japan," she said. "And when all of a sudden we talk about using nuclear weapons in the Taiwan Strait, we are very clearly blurring the commitments we have made."
Taiwan is not a formal US ally, and Giovannini says American thought leaders are conflating a loss of primacy in the Indo-Pacific with an existential threat.
She is sure that China is watching Kroenig and Weaver's rhetoric, even if their reports may not represent US policy.
"The Chinese read everything that we write about them. Everything," she said.
The Chinese foreign affairs ministry and embassy in Washington, DC, did not respond to requests for comment from BI.
Kroenig, a professor at Georgetown University, was commissioned last year by Congress to advise the US on nuclear strategy.
He believes that if Taiwan falls, so too will America's credibility as a leading power. That makes Taiwan a core US interest, he said, and one the US should consider protecting with nuclear weapons.
Concerns are now growing that China is catching up in conventional arms, with missiles that can kill aircraft carriers and long-range strikes threatening Guam.
Some observers speculate that if Beijing thinks the gap has truly closed, it may be willing to invade on the gamble that the US won't risk conflict. After all, should the US go to war and fail to win handily, global faith in Washington would crack.
"One way deterrence could fail is if Xi Jinping thinks: 'Maybe this will be easy, maybe I can get away with it,'" Kroenig said.
Hence, his November report suggested that the US move past strategic ambiguity and declare Taiwan part of its nuclear umbrella. It would essentially tell Beijing that an invasion of the island risks nuclear war, he said.
To back up that threat, he said, the US must show that it has the capability to nuke targets like navy ships, military installations in the South China Sea, and even on the Chinese mainland.
"What's the benefit of reassuring Xi that our nuclear weapons are not relevant?" he said.
Weaver's report works off a forecast for 2027, when China is expected to possess 700 nuclear warheads. He, too, told BI that deterrence is the main goal, and said his paper doesn't call for the US to rely on tactical nuclear strikes for Taiwan.
But if open conflict does break out, they could be useful as a warfighting tool, he said.
"The Chinese amphibious landing force would be a stationary target for hours if not days, and it would be off the coast," he said. "So relatively low-yield nuclear weapons could destroy that amphibious force and do little to no collateral damage onshore in Taiwan."
A heavyweight in nuclear policy, he said his intention was to advocate for more strategic options for the US president. There is concern that if the US is stretched across two theaters at once — potentially one with Russia and one with China — it would need solutions like nukes to deter or fight one of those wars.
"It's not the preferred course, but it's an option that the Chinese need to understand is there, and they need to take seriously," he said.
A spokesperson for the US State Department declined to comment on Kroenig and Weaver's reports, but said the US maintains a "very high bar for nuclear employment.'"
"The United States would only consider the use of nuclear weapons in extreme circumstances to defend the vital interests of the United States or its Allies and partners," they said.
Marshall Billingslea, the former US special presidential envoy for arms control, told BI he didn't see why the reports caused such a stir.
"We do already keep track of and plan for and are able to strike targets in China if that should become necessary. It's important that the Chinese understand this," said Billingslea, who led US negotiations with Russia in 2020 on the New START Treaty.
And it is China's actions that should be cause for worry, he added.
US intelligence has charted a sudden burst in nuclear build-up from Bejing, which bolstered its arsenal to 500 warheads in 2023, up from 400 in 2022. China denies any expansion, and concerns abound in the US that it may soon become a rogue nuclear superpower.
"Since the dawn of the atomic era, we have not had a three-way nuclear arms race, but that is precisely what China is creating, that unpredictable, unstable dynamic," said Billingslea.
Rebeccah Heinrichs, director of the Hudson Institute's Keystone Defense Initiative, agreed with Kroenig and Weaver's core thesis, also describing a Taiwan invasion as a "clear threat to US vital interests."
"It would be foolish not to give the President of the United States and his military forces the most effective means to convince the PRC it will not take Taiwan at an acceptable cost," she said.
When Weaver was asked if more aggressive rhetoric from the US could be used by China to justify its nuclear build-up, he said Beijing's expansion is happening regardless.
"They were already doing that," he said. "They were doing that long before Matt and I wrote our analyses."
On the other hand, Jake Werner, acting director of the East Asia Program at the Quincy Institute for Responsible Statescraft, raised concern that the November reports would empower anti-US parties in China.
"The American public doesn't understand that there are different positions in the Chinese debate. There are people who are very aggressive, there are people who are very cautious," he told BI.
"Because threat perceptions are so elevated on the Chinese side, saying things like this is bound to be used in a way that exacerbates fear in the Chinese public, if not among officials," he said.
Kearn of St. Johns University said the US has more than China to worry about if it makes the threat; it could lose credibility with allies like South Korea or Japan if they believe Washington is bluffing.
"On what foundation of diplomatic or political relations can you even pretend to have credibility in that situation, of threatening the use of nuclear weapons for the first time since 1945?" he said.
He added that threatening war — much less nuclear war — over Taiwan would be deeply unpopular at home.
"That's not where the American people are, by any poll I've ever seen," he said.
Kroenig believes the gravity of nuclear escalation and annihilation will still give Beijing pause if it considers invading Taiwan.
"Even if they suspected it's a bluff, if they think there's even a 10% chance of nuclear war, that would be pretty significant to strengthen deterrence," said Kroenig.
