The Return of Great Powers: Russia, China, and the Next World War

by Jim Sciutto

The Return of Great Powers documents the end of a world order built up over decades, dealt a deathblow by the largest war in Europe since World War II. This reversal represents strategic shifts by Russia, the United States, and now China—with each side reappraising the others’ objectives and remaking their own. The new order of three great powers is lengthening and hardening dividing lines among the powers while breaking diplomatic and economic ties among them. It is sparking military expansions while reducing military-to-military communication. It is inflating nuclear arsenals and new categories of weapons while dissolving the treaties that regulate such weapons. It is drawing in middle powers and regional interests in unexpected, inconsistent ways. The return of great powers has upended the post–Cold War global order and replaced it with a new, less stable one.

“What keeps you up at night?” In Burns’s view, the greatest risk in this new era of great power competition is not necessarily a deliberate decision to go to war, but a small encounter among the great powers spiraling into something far bigger. “Any day you could have two military aircraft flying too close. Somebody clips another one. You could be off to the races, especially without a reliable mechanism to communicate with one another,” Burns said. “So that’s why I’m a huge believer in intelligence channels. If you’re not talking to them, it’s very hard to be able to manage crises, which inevitably are going to come up.” “Off to the races”—a consistent fear I heard from senior leaders I interviewed is of momentum toward conflict.

CIA Director

Burns’s message was direct: the US could see the Russian buildup. What was Putin’s intention? The scale of the Russian invasion force was staggering. By early 2022, according to US intelligence assessments, Russia would have close to 75 percent of its conventional forces postured against Ukraine. This included some 120 of Russia’s total estimated 160 battalion tactical groups, or BTGs—Russia’s primary combat units, encompassing seven hundred to nine hundred personnel, each with infantry, armor, artillery, and intelligence-gathering capabilities—all deployed about forty miles from Ukraine. Thirty-five of fifty known air defense battalions, fifty of its eighty medium and heavy bombers, and some five hundred fighter and fighter-bomber aircraft were deployed against Ukraine too. Russia was moving the bulk of its entire conventional military force to Ukraine. Putin’s message was unwavering. The force was necessary to protect Russia. Ukraine and NATO were the real threats to peace.

I drafted an email to then president of CNN Jeff Zucker to lay out the situation as I understood it. My immediate goal was not to report the US intelligence assessment of Russia’s invasion plan, but to warn CNN to prepare for what would become—if the intelligence bore out—a monumental and dangerous news story for our times. Most of my colleagues, myself included, had been in news only after the collapse of the Soviet Union. We had done our work after the fall of the Berlin Wall, after the dissolution of the USSR and Warsaw Pact, and as many former Soviet republics gained independence and even joined NATO. The stories we had covered were particular to a post–Cold War world: regional wars, not global ones.

Putin’s mounting threat to Ukraine was not a complete surprise to Helsinki. Finnish officials had seen warning signs from Putin and the Kremlin for more than a decade. “The people grew more and more disillusioned about Russians. And that started, I would say, at the latest in 2008 with the attack on Georgia,” said Mikko Hautala, ambassador of Finland to the United States. “There was a discussion in Finland that Russia is actually becoming something that it was not before: a threat.”

“He tried to define Finland permanently outside the alliance,” said Hautala. “And usually historically, if a great power with which you have a common border tries to block you and put you in a cage, then it’s not a good idea to stay in the cage—at least you have to try to make sure that nobody locks the cage.”

In the years preceding the military buildup, Vladimir Putin had been quietly building a historical pretext for war. He based his claims on dusty maps and manuscripts in agencies and institutions charged with caretaking the history of the Russian state going back centuries. Quietly, Putin was aligning Russian academia and bureaucracy behind his plans. He transferred control of agencies and institutions few had ever heard of—the Federal Archival Agency, the Russian War History Association, the Russian Historical Society, the Russian Geographical Society—under the Kremlin and therefore under his personal control. “There was this mushrooming of these historical associations,” said Ambassador Hautala. “That was the time when we did realize that Russia actually has a fully fledged, state-led history program in order to explain things according to their politics and political needs,” he explained. “Up until that point, history was an open field of study, and you had different voices, and the mainstream was still academically serious. But then, we realized that this country has adopted the Soviet way of top-down historical definition and history is part of the state policy.” In short, Putin had been rewriting the history of Russia and—crucially—Ukraine to create a justification for war, bending what even his own fellow Russians knew and believed of history to suit his view and ambitions in the present. The new history stated that Ukraine was and always had been part of Russia and ...

“We are committed to the peaceful and diplomatic path, we will follow it and only it,” Zelensky said in a televised address to the nation. “But we are on our own land, we are not afraid of anything and anybody, we owe nothing to no one, and we will give nothing to no one,” he added.[4]

“We adhered to the spirit of The Art of War: ‘Rely not on the likelihood of the enemy’s not coming, but on our own readiness to receive him,’ ” said Colonel Chang Chi-Ming the commander of Taiwanese ground forces stationed on the Penghu Islands, quoting Sun Tzu’s famous work. He, like many others in Taiwan, immediately saw a direct connection between the war then engulfing Ukraine and the one they were now training for. In one moment, on opposite ends of the globe, Russia’s invasion of Ukraine fanned fears of not one but two wars for national survival. “We harbor no unrealistic fantasies about peace,” Chang said. “Based on the conviction that defending the homeland is our duty, our national military strives to serve as the strongest line of defense for the country.” He added, “When the Russo-Ukrainian war broke out, I realized that it was a battle for our survival.”

I understood the doubts from years covering the intelligence agencies and holding a top secret security clearance myself. Over decades, the US had built the most comprehensive and capable intelligence-gathering apparatus in history, but its products required reading with a critical eye. However, the assessments of Russia’s invasion plans were different, because the invading force was visible, laid out right before the watchful eyes of US surveillance satellites and aircraft. And what they saw was alarming. Russia was readying for war. “Iraq’s weapons of mass destruction were phantoms,” I told them. “The Russian invasion force is right along the border in 3D. They’re not guessing this time.” US agencies had collected other revealing intelligence as well. In a triumph of signals collection, the intel community had penetrated Russian communications networks. They now had direct access to Russian battlefield communications. They were listening in real time as Russian commanders discussed in detail preparing and positioning their units for attack. Yet the doubts extended far beyond our newsroom, with some NATO leaders downplaying or even dismissing the more ominous warnings of an impending Russian invasion. Tensions broke out into the public discussion even between US and Ukrainian officials. On January 28, Ukrainian president Zelensky told reporters in Kyiv, “There is a feeling abroad that there is war here. That’s not the case.” Ukrainian officials were fearful in part that t...

Quality and quantity have proved more or less effective. Small, mobile units gave Ukrainian forces the advantage during Russia’s plodding assault on Kyiv. Those small Ukrainian units were able to assault miles-long Russian armored convoys almost with impunity, in the end repelling what was intended to be the decisive force of the Russian invasion within days of the start of the war. “As a Marine infantryman—stalkers and hunters—clearly, the Ukrainians have done that in spades,” John Kelly, retired US Marine Corps general and former chief of staff in the Trump White House, told me. “The beauty of what the Ukrainians are doing—small units—they’re out there hunting.”

Military observers have repeatedly pointed to the Ukrainian forces’ ability to innovate in real time. One notable example is how they adapted to fire their artillery for far longer and with greater frequency than had been assumed possible. Dire necessity, said Representative Quigley, was the mother of adaptation. “They learned how to adjust on the fly,” Quigley said. “You’d be surprised how fast you learn when your ass is on the line and you don’t want your spouse to be raped.” Many commanders credit training by NATO forces, which accelerated following Russia’s first invasion of Ukraine in 2014. In particular, under western instruction, Ukrainians invested their officers and NCOs with the ability and agency to make their own decisions on the battlefield—to take the initiative and adapt on their own. “The US is typically like that,” said General Kelly. “Our troops are very well trained. Our troops are the best at it: ‘Take the hill,’ commanders say, ‘and I’m not going to tell you how to do it.’ ” Russian forces, on the other hand, reserve decision-making to only the highest ranks. “The Russians are very top-down, very controlling,” said Kelly. “One thing Stalin would never buy is too many people taking the initiative. Communist regimes didn’t want their people thinking. Warfare is so chaotic. If you haven’t developed your people so that they’re very good on their own, I think you will always lose to someone who is doing that.” As attention increasingly focuses on China’s po...

In brief, Milley argues that the choice for world leaders today is between a system of albeit imperfect rules, or no rules at all and what he describes as a “Hobbesian . . . dog-eat-dog world.” “My concern today is that the international system is weakening that potentially could make great power war more likely rather than less likely,” he continued. “And we have to guard that system very jealously, or you’ll have problems in the future.” To add to the danger, this dissolution of the old order is happening, as the great powers have far greater weapons at their disposal and far fewer agreements to limit them. “Great power war today is exponentially more dangerous than it was in World War I or World War II because of the advent of nuclear weapons, but not just nuclear weapons,” said Milley. “The conventional weapons—they are unbelievably more powerful than they were back in those days.”

Putin writing, “Our countries, together with like-minded actors, have consistently advocated the shaping of a more just multipolar world order based on international law rather than certain ‘rules’ serving the needs of the ‘golden billion.’ ”[15] (The “golden billion” is a conspiracy theory that the world is ruled by a wealthy elite serving the interests of the richest one billion people.)

In our conversations, then Joint Chiefs Chairman General Mark Milley dubbed this his “declaratory policy” of international affairs. “My read of history is, when foreign heads of state make declaratory policy and it’s publicly stated and then repeated several different times, it is in people’s interest to believe them—what I call declaratory policy in international politics,” Milley told me. “When Saddam Hussein says publicly he’s going to invade Kuwait, it’s a good idea to listen to him, right? When Hitler says, and writes in Mein Kampf, I’m going to kill the Jews, you got to listen to him. When Kim Il Sung says, I’m going to invade South Korea, probably listen to him. When Mao Zedong says, If you get within twenty-five miles of the Yellow River, I’m coming across the border . . .”

Sage advice

In late October, the US gathered intelligence indicating that Syria would provide Hezbollah, Iran’s proxy in Lebanon, with the Russian-made surface-to-air SA-22 missile system. According to US officials, the Russian mercenary group, Wagner, was the conduit for the exchange.[44] A senior US military official told me that such an exchange would not have taken place without the explicit approval of the Kremlin. This was a wartime gift to Hezbollah from Russia—and an impactful one, giving the militant group the capability to target Israeli warplanes over Lebanon.

Israeli officials noticed. “For the first time since the withdrawal from Afghanistan—even the first time since 2003—the U.S. is advancing large military assets into a war zone—and engaging,” Michael Oren, the former Israeli ambassador to the US, told me. And that message, Oren said, was being heard far beyond the Middle East. “Iran, Russia, China—they all drew conclusions about America’s unwillingness to project power. Even in Ukraine, Biden wasn’t willing to lose a single US soldier. That suddenly has changed.” To Oren’s point, the US assets weren’t silent. US warplanes struck Iran-backed militias in Iraq and Syria after they targeted US forces stationed there. And a US destroyer shot down missiles fired at Israel by Iran-backed Houthi rebels in Yemen. “America is going right at this axis—right at the vortex, the focal point that is Iran,” Oren told me.

Australian leaders had previously calculated their future was equally as a citizen of Asia as of the West—and they had tweaked their country’s trade and defense policies accordingly. Yes, China was authoritarian, but there was no questioning its growing economic and military power in the region. Better to get along. But Beijing had overplayed its hand, interfering in Australian politics and, when displeased with Australian trade and foreign policy, applying economic pressure by reducing purchases of Australian exports. By entering AUKUS, Australia threw its lot in fully with the US and the West—and the US and the West gained a powerful new means of projecting power in the region with a weapon, the fearsome nuclear submarine, that is seen as more and more likely to determine the outcome of any future military conflict among the great powers. By late September 2022, as The Wall Street Journal first reported,[49] the Biden administration was considering a plan to speed up the delivery of nuclear submarines to Australia in response to growing Chinese military aggression in the region.

As relations between Russia and NATO have worsened, Moscow has looked for new opportunities to threaten and disrupt the alliance. In 2018, Russia deployed nuclear-capable Iskander missiles to Kaliningrad, according to Russian state media. The Lithuanian government has since publicly warned that Russia has put nuclear warheads into place as well. Secretary of State Antony Blinken and other senior US officials have told me the US believes Russia knows it cannot credibly take on the alliance. But do NATO commanders agree? A NATO COMMANDER’S VIEW “I hope that this is really the case,” Rear Admiral and Commanding Officer Marx said. Like the seasoned commander he is, with more than three decades in the German Navy, Marx takes care to consider all possibilities. “If the regime is under so much pressure—so in danger—that it needs to take measures of last resort, then you never know what will happen in this regard. But at the moment, I think by clear strategic messaging, by making sure that the capabilities [are] available and operating in the vicinity, at least the communication and the messages are [delivered] in such a way that there is no room for misunderstandings.”

NATO leaders today emphasize the need for clearer communication of the alliance’s commitments and capabilities. The VJTF is a sentry, in effect, on NATO’s northeastern frontier.

The two sides play by very different rules in these delicate encounters. NATO ships and aircraft operate under strict rules of engagement, maintaining at least five nautical miles’ distance from Russian ships and aircraft. Russian pilots operate under different rules, or no rules at all. “They don’t care,” one pilot told me. While NATO aircraft fly with their transponders on—deliberately visible to the other side—many Russian aircraft do not. For René, the chopper squadron commander, the dangers of these behaviors and this new threat environment are very real. “I have to be quicker in the air, more vigilant. We fly armed more often—always capable to defend ourselves and our force,” René said. The threat environment means a whole new mission for NATO forces in the Baltic. Before the Ukraine invasion, they told me they operated more like a coast guard. Now they are again a true navy. “We changed back to our main missions: anti-submarine warfare, anti-surface warfare,” René told me. “So we do multi-role missions for the frigate. We are the ‘eagle-eye’ view, and we extend the range of the maritime picture for the frigate. And we have to be capable to switch every hour from an anti-submarine mission to an anti-surface mission to passenger transport to deployment of special forces.”

there is before Ukraine and after Ukraine, in terms of operations and outlook. On board the Mecklenburg-Vorpommern, the Ukraine invasion remains a clear turning point. “The attack on Ukraine really changed the mindset in all of Europe,” Marx told me. “People realize the way the Russians are fighting the war in Ukraine—not caring about their own people.” “After the attack on Ukraine, our chief of the navy ordered that everyone who is available goes out and shows the readiness of the German Navy,” Marx told me. “And this was similar to all the other navies during that time. And quickly they were more than two hundred ships available sailing around, indicating that the alliance is ready and can do any defense job that’s required. And I think this was also a very strong signal towards the opponent: ‘Do not even dare.’ ” “Do not even dare”—his words struck me. The task force’s designation Very High Readiness has meaning. Implemented by NATO immediately following the Russian invasion of Ukraine, it means this task force is ready to act in any mission at any moment.

NATO commanders say Russian forces exhibit their greatest strengths in electronic warfare, underwater operations including submarines and unmanned underwater vehicles, and advanced missile systems. Many of those systems have been on display in Ukraine, including hypersonic missiles capable of evading even the most advanced missile defense systems. In late 2022, as I reported at the time for CNN, Russia had been preparing to test a new nuclear-powered torpedo before it scrapped the test because of possible technical problems.

Between 1999 and 2018, the number of frigates and destroyers in European navies dropped by 32 percent, and the number of submarines by 28 percent. As the German Council on Foreign Relations noted in an April 2020 policy brief, “Even though defense budgets slowly recovered toward pre-crisis levels after 2014, capabilities did not. Nationally as well as at EU and NATO level, significant gaps still exist.”[5]

Estonia is an early-warning system for NATO, and Estonian leaders consistently deliver blunt warnings about the threat from Russia. In military terms, they are—quite literally—a tripwire for a Russian invasion. “Tripwire” is, in fact, how NATO describes its defense strategy for Estonia, Latvia, and Lithuania if Russian forces were to attack. NATO’s eastern-facing allies interpret and convey Russia’s threat very differently than its western allies do. Estonian officials—presidents, prime ministers, foreign ministers, and military commanders—have been telling me for years, even prior to the 2022 Ukraine invasion, that “We are next” in Russia’s crosshairs. They do so without melodrama and simply by pointing to history. NATO’s Very High Readiness Task Force dropped me off in the Estonian capital of Tallinn, where I was to meet with one of the most no-nonsense voices on Putin’s Russia, Estonian prime minister Kaja Kallas. I was arriving the same day she was announcing a new coalition government, following elections her party had won the month before. We met in the downtown hotel where the new coalition’s press conference would take place. Estonia’s role in NATO had been a central issue in the campaign. The country’s far-right party EKRE had vowed to curtail Estonia’s support for Ukraine. Kallas had promised to increase it. Sharing a coffee before she would join her coalition partners onstage, Kallas told me one of her first tasks in the new government would be to raise taxes to...

It’s a reality that Kallas believes NATO’s western-facing allies simply don’t understand. “They have much better neighbors,” she said. “They don’t deal with this. For them, the security issue is a nice intellectual conversation to be having. It’s not an existential threat like it is for us.”

To Kallas, the debate among western leaders about whether Ukraine should trade territory for peace with Russia is dangerous. If NATO is willing to watch Ukraine cede territory to Russia, might the alliance ask Estonia to do the same someday? “If they are thinking that they are protecting themselves by sacrificing something that is not dear to them—a small country, 1.3 million people, who cares?” she said. “The US doesn’t even know where we are.” Kallas is a leader deeply conscious of history. In two hours over coffee, she cited half a dozen books she’d been reading—on Russia, on Putin, on the history of World War II and the Cold War—a leader searching the past for lessons to save her country as an independent state.

Kallas herself is unmoved by the idea of land for peace. More than once as we spoke, she recalled Winston Churchill’s warning about Hitler before World War II: “Appeasing the dictator is like feeding the crocodile, hoping that you are the last to be eaten.”

Russia is of course conscious of history as well, distant and more recent. In Kallas’s view—and she is not alone—one of the most influential lessons for Putin was the West’s muted response to Russia’s previous invasion of Ukraine in 2014. “If you see how they have evolved over time, first, they were ashamed that they were actually taking territory from their neighboring countries,” she told me. She continued, “Then they saw that nothing happened. Nothing happened. So next time they were braver.”

To Kallas, though, the historical context is that this has been Russian behavior for more than a century, never truly changing from 1919 to 1940 to 2014 and to 2022 and beyond: Russia takes what it can get and then pushes for more. “That is the lesson we learned from history, and that is the lesson for Ukrainians as well: that they just can’t stop, otherwise they’re going to lose territory,” she told me. “They have already lost people, but they’re going to lose more if they give in to Russia. It’s never going to stop.”

Estonians’ doubts—informed by more than a century of suffering under Russian broken promises, aggression, and subjugation—did not surprise me. But their doubts about their own allies did. “They hope that this will go away, and they don’t really realize that it’s here to stay. That’s a new normal. And we have to actually prepare,” Prime Minister Kallas said. Beyond talk of land for peace in Ukraine, Kallas sees worrisome precedents in NATO’s sometimes halting military support for Ukraine. “What I’m worried about right now, when they say, ‘Give Ukraine what you have,’ and then they say that they don’t have more, what if [Estonians] need help? Then they won’t have the people or the equipment to come here.” In her press conference that day at the downtown Tallinn hotel, as she announced the new ruling coalition and made the case for tax hikes to pay for her nation’s defense, Kallas described security as her government’s greatest responsibility. “Without security, we don’t have to talk about anything else. That’s why we’re increasing our defense expenditure to three percent [of GDP] in the coming years,” she said. She went on to emphasize that all nations must “do everything possible to secure themselves,” noting an article from the NATO treaty that doesn’t get discussed as often as the Article 5 commitment to mutual defense. “Before Article 5, there’s Article 3. Article 3, in the NATO treaty, says that everybody has to make everything possible to defend themselves,” she told m...

Kallas’s study of history is intended to avert a war with Russia, not to start one. Throughout our many conversations, she expressed deep fears about how devastating such a new war with Russia would be for Estonia and for Europe. She wants to learn from her predecessors’ decisions—good and bad—to help prevent another, and the hundreds of tanks aren’t about offense, but defense and deterrence. “We have fought together before,” she said of Estonia and Russia. “I sound like we are going to have a war. I don’t want to say that. I hope that we are going to avoid the war.” The history of this new great power competition in Europe continues evolving under our eyes and will into the next months and years. And so she and her fellow European leaders must make decisions today with outcomes that will become clear only years later—decisions such as how to defend Ukraine now, including how many tanks to send or whether to send fighter jets, and how to defend themselves and their NATO allies in the east. “The dilemma that the prime ministers have,” she said, “is that we have to make decisions. But we will [only] know if they are right or wrong in five years’ or ten years’ time. But you have to decide now, if we go and send the planes there, does it mean that the war will stop, or does it mean that the war will expand?” More and more, she sees power in the alliance migrating toward allies with greater urgency about the Russian threat. “The center of gravity in NATO,” she told me, “is movi...

The mechanized infantry combat team stationed at Hen Hill Army Base on one of the ninety Penghu Islands is preparing every day for invasion. Taiwan’s military is careful about allowing journalists access to its bases on this archipelago, strategically positioned in the disputed waters of the Taiwan Strait.

With such short distances—Penghu is just eighty-six miles from the Chinese coast, less than the distance from Florida to Cuba—Taiwanese forces must train to respond within minutes. To make them more difficult targets for any Chinese attack, Taiwanese military units are deliberately dispersed across the islands. I found similar urgency at the nearby Magong Air Base, home to a rotating squadron of “indigenous defense fighters,” the jets that form the backbone of the Taiwanese Air Force. There, squadron commander Lieutenant Colonel Pi Shih-Chuan—who, with Maverick-like bravado, shared his call sign, “Big”—explained that his squadron trains to scramble within five minutes, yet almost always gets airborne even faster.

For years, each party has established and advertised its red lines. For Taiwan and the US, the red line has been a Chinese invasion, or any attempt by China to take Taiwan by force. For Xi, the red line has been Taiwan formally declaring independence or—less definitively—moving too close to independence for Chinese leaders’ comfort. But in recent years, under an increasingly aggressive Xi, many fear China has lowered its threshold for military action. The Chinese leader, fresh off securing an unprecedented third term and dispensing with China’s decades-old term limits, simply wants to reunify the island with the mainland to solidify his historical legacy and is just waiting for the right time to do so at minimum cost.

In fact, despite the focus on what Beijing has learned from the Ukraine war, Taiwan may be gaining the most important lessons from the conflict. Just as Russia’s 2014 invasion sparked Ukraine to institute major military reforms, and the West to boost training of Ukrainian forces and the influx of weapons, the full-scale 2022 invasion of Ukraine sparked a similar rethinking of Taiwan’s military preparations and defense.

What does such help look like? Many in Taiwan and among its allies have settled on the “porcupine” strategy. Republican US senator Roger Wicker, ranking member on the Senate Armed Services Committee, laid out the strategy in stark terms on the Senate floor in February 2023. “We need to turn Taiwan into a porcupine so that Xi Jinping wakes up every day and concludes that an invasion is not worth the costs,” Senator Wicker told his colleagues. “Now, why do you say a porcupine? Any wolf has the ability to kill a gentle porcupine. And yet such an attack rarely occurs in nature. The defense of the porcupine’s quills, which can rip through the predator’s mouth and throat, is the deterrent that protects it from attack by the wolves. That should be our approach for Taiwan’s defense.” “Rip through the predator’s mouth and throat”—stark words from a US senator, and ones Beijing certainly heard. But they capture the intention: to make an attack on Taiwan as devastating for China as it would be for Taiwan.

In October 2021, as CNN prepared for a town hall with the president, I suggested that my colleague Anderson Cooper follow up on Biden’s comments and ask him if the US would indeed come to Taiwan’s defense in the event of an attack by China. Not once, but twice, the president answered yes. “China just tested a hypersonic missile. What will you do to keep up with them militarily? And can you vow to protect Taiwan?” Cooper asked. “Yes and yes,” Biden answered, adding, “Militarily, China, Russia, and the rest of the world knows we have the most powerful military in the history of the world. . . . I don’t want a Cold War with China. I just want to make China understand that we are not going to step back. We are not going to change any of our views.”[6] “So, are you saying that the United States would come to Taiwan’s defense if China attacked?” Cooper pressed. “Yes,” Biden answered, repeating, “Yes, we have a commitment to do that.”[7]

“I would just tell you that, going back to a declaratory policy of national leaders, when a national leader says, ‘I will do A, B, or C,’ it’s worthwhile believing them—that’s my read of history,” said Milley. “When foreign heads of state make declaratory policy, and it’s publicly stated and then repeated several different times, it is in people’s interest to believe them. The old saying is ‘Great powers don’t bluff.’ Typically speaking, these guys do not bluff, and they say what they mean.”

for two years, as chief of staff to the US ambassador to China, I had the highest-level security clearance, Top Secret/Secret Compartmented Information (TS/SCI), which allows access to some of the most sensitive national security intelligence. During my assignment, I read numerous classified intelligence assessments. And one lesson I learned reading them is that they are rarely, if ever, 100 percent certain. Most often, they are based on a combination of concrete intelligence, including imagery and communication intercepts, and analysis, to generate what are essentially informed estimates. Some assessments lean more on analysis than hard information. For instance, US assessments of Russian plans to invade Ukraine, which turned out to be correct, relied in large part on imagery of a massive buildup of Russian forces around Ukraine and intercepted communications among Russian commanders discussing an invasion. The US assessment of Iraq’s nuclear weapons program prior to the 2003 Iraq invasion leaned far more on the latter, with a heavy dose of political influence to imply certainty where there was none. But this new assessment of a possible Russian nuclear attack included substantial doses of both hard intelligence and analysis. “It’s never a cut-and-dry, black-and-white assessment,” the first senior administration official told me. “But the risk level seemed to be going up, beyond where it had been at any other point in time.”

early November 2022, German chancellor Olaf Scholz traveled to Beijing to meet with Chinese president Xi Jinping. Russia’s nuclear threat in Ukraine was a central topic of their meetings. And following their talks, Scholz told reporters, “President Xi and I agree: nuclear threats are irresponsible and incendiary. By using nuclear weapons, Russia would be crossing a line that the community of states has drawn together.”[13] China’s official readout of their meeting contained a similar warning using similar language. China’s state-run Xinhua News Agency reported the two leaders had agreed to “oppose the use of or the threat to use nuclear weapons, advocate that nuclear weapons cannot be used, and that nuclear wars must not be fought, and prevent a nuclear crisis in Eurasia.”[14] Prime Minister Narendra Modi of India was even more forthright in his public criticism of Russia and its nuclear threats. At the Shanghai Cooperation Organization Summit in Uzbekistan that September, during a bilateral meeting with Putin, Modi seemed to chide the Russian leader, saying, “Today’s era is not of war” and encouraging him to “move onto a path of peace.”

The US has been navigating this nuclear scare as the world enters a new period with fewer and fewer treaties or even the outline of treaties to govern the expanding conflict. There are no cyber arms control treaties. There is no comprehensive agreement governing the weaponization of space. And two of the most crucial nuclear arms control treaties between the US and Russia—the Intermediate-Range Nuclear Forces (INF) Treaty and the Anti-Ballistic Missile (ABM) Treaty—no longer hold. The US withdrew from ABM under President George W. Bush in 2002 and from INF under President Trump in 2019, accusing Russia of repeated violations. “We need at some stage to reestablish arms control,” NATO Secretary General Stoltenberg told me, “because all the big arms control agreements that we were able to reach, actually during the Cold War and in the years after the Cold War, have just been dismantled.”

Prime Minister Kaja Kallas of Estonia recounted a dinner she attended with other senior officials from NATO allies during the Munich Security Conference in February 2023. “We had a very interesting dinner regarding Russia,” she told me. “What was interesting was that I heard very high officials from Germany and Luxembourg [and other] countries, say, ‘Oh, we can’t do this because it would provoke them to use the nuclear weapon.’ ” In the meeting, Kallas responded with a mild scolding. “I said there that if Russia is going to use [a] nuclear weapon, it’s going to be either on Ukraine or on us, but not on Germany, not on Luxembourg. If we are not afraid, so shouldn’t you be. If Ukrainians are not afraid, you shouldn’t be either,” she said. Russia, she argued, stokes and capitalizes on those fears to its advantage. “So they know. They use this threat because they know that the westerners really are afraid of this. And if you look at the damage that they have [already] caused in Ukraine, it’s bigger than any nuclear bomb.” Kallas believes that the risk of falling victim to Russian nuclear brinksmanship extends beyond Ukraine—that by retreating in the face of Russian nuclear saber-rattling, the West will empower authoritarians around the world. “Some are saying we shouldn’t talk about accountability, because then Putin is going to be the rat in the corner, and he has nothing to lose. So he will use [a] nuclear weapon, because he has no way out,” said Kallas. “But I don’t really ...

For General Milley, it comes down to core values and core interests. That is, sovereignty is not just a noble idea but a practical one to keep the peace. “[The Ukraine war] is a frontal assault on the rules. And rule one says that large, powerful countries cannot arbitrarily change the international boundaries of smaller, weaker countries through the use of military force,” Milley said. “If that understanding goes away, then your risk of great power war goes up exponentially. That’s what’s at stake in Ukraine.”

US military and intelligence officials at the highest levels tell me they take care to listen to Baltic leaders. And what they hear is that NATO must not forget Russia has already proved it is capable of aggression. “In dictatorships . . . you only care about your power, the cronies around you keeping you in power,” Prime Minister Kallas told me. “You care about the army and the police and the power structures being happy, because they keep you in power. And all else, you don’t care.”

Those who rationalize as realpolitik the Russian invasion of Ukraine, or a potential Chinese takeover of Taiwan, risk rationalizing the next invasion. As Estonia’s Kallas said, evoking Churchill, the hungry crocodile eventually comes for you. For the many officials around the world I interviewed for this book, the simplest lesson—as relevant today as it was in 1939—is that acts of territorial aggression by the great powers cannot succeed without then incentivizing the next acts of aggression. “We have to totally discredit the tool, policy tool, of aggression,” said Kallas. “You can’t walk away with more than you had before. Otherwise, it’s incitement to aggression.”