It is one of the most impressive intelligence successes of the 21st century and one of its most terrible failures at the same time. Before February 24, 2022, the CIA and Britain's MI6 put together an incredibly detailed picture of Vladimir Putin's plans to launch a full-scale invasion of Ukraine. They figured out the invasion routes, the staging areas, the schedule, and even the specific military goals. One of these was a daring airborne attack on an airport just 10 kilometers from Kyiv that was meant to help the Ukrainian government fall quickly.

But when it really mattered, almost no one believed them.

The Guardian put together the story by talking to more than 100 high-ranking intelligence officials, military personnel, diplomats, and political insiders from the US, UK, Ukraine, Russia, and Europe. It shows a series of mistakes and lies that left Europe shocked by the biggest land war on its soil since 1945. The CIA and MI6 got the situation right, but they didn't accurately predict what would happen, assuming that Russia would win the war quickly. European intelligence agencies didn't think that a full-scale war in Europe could happen in the 21st century. And most importantly, Ukraine's own president ignored increasingly urgent warnings for months, calling them scaremongering, until Russian missiles began hitting Kyiv in the early morning hours.

Four years later, the lessons from this intelligence story have big effects on a world that seems more unpredictable than it has in a long time. The most important lesson may be the one that goes against common sense: it's risky to ignore a situation just because it doesn't make sense.

Putin's Isolation and Ideological Drift: The Seeds of War

The CIA was never able to figure out for sure when Putin first decided to invade. But later, analysts found that the ideological groundwork went back to early 2020, when Putin pushed through changes to the constitution that would let him stay in power until 2036. The Russian president went into hiding for a long time during the COVID-19 pandemic and read a lot about Russian history. Multiple intelligence sources believe that this made him even more sure that Ukraine's independence was a historical mistake.

In the summer of 2020, things that happened in Belarus made this path even stronger. When a lot of people protested against Belarusian dictator Alexander Lukashenko, Putin stepped in to help the regime, making Lukashenko even more dependent on Moscow. This would have big strategic consequences: Belarus would later be the most important northern base for the invasion's push toward Kyiv. The poisoning of opposition leader Alexei Navalny in August 2020 and his arrest when he returned to Russia in January 2021 made it even harder for people to speak out against Putin, removing any possible obstacles to a big military gamble.

In the spring of 2021, the first clear signs that Russia was planning a war appeared. Russian troops began to gather along the border with Ukraine and in Crimea, which Russia had taken over, supposedly for training exercises. The size of the buildup scared Washington so much that President Joe Biden called Putin directly to ask him to calm down and suggested a summit meeting. Avril Haines, the U.S. Director of National Intelligence, later said that Biden "expressed concern about the troop buildup and called for de-escalation, and also suggested holding a summit in the coming months, which we knew Putin would be interested in."

On June 16, 2021, the two leaders met in Geneva. The summit seemed to calm the situation down right away. Russian soldiers pulled back. The threat seemed to be over.

It hadn't.

Putin's Ideological Manifesto: "On the Historical Unity"

Four weeks after the Geneva meeting, on July 12, 2021, Putin put up a 5,000-word essay on the Kremlin's official website called "On the Historical Unity of Russians and Ukrainians." The treatise, published in both Russian and Ukrainian, traced its origins to the ninth century and the legacy of Kyivan Rus', asserting that Russians, Ukrainians, and Belarusians formed a singular "triune" nation. Putin said that Ukraine's sovereignty was only real when it was working with Russia, and that the country's move to the west was the result of foreign interference that had been going on for hundreds of years.

The essay was not just an academic exercise. The Carnegie Endowment for International Peace said it was a historical, political, and security basis for military action against Ukraine. Anders Åslund from the Stockholm Free World Forum went even further, saying it was "one step short of a declaration of war." The Russian paper Moskovsky Komsomolets called it "Putin's last ultimatum to Ukraine." The essay was later required reading for members of the Russian military, which was probably the most worrying thing. This was ideological preparation for the troops who would cross the border seven months later.

Ukrainian President Volodymyr Zelensky first responded by making fun of Putin, saying that the Russian leader clearly had too much free time. Former President Petro Poroshenko made stronger comparisons, saying that the essay was like Hitler's speech justifying the division of Czechoslovakia in 1938. But the essay's deeper meaning got lost in the summer noise. The chaotic withdrawal from Afghanistan took up the time of both London and Washington within weeks.

"This Doesn't Look Like Exercises": The Intelligence Picture Gets Clearer

In September 2021, Russian troops started to build up along the border with Ukraine again. In less than a month, it had grown too big to ignore as something normal. Satellite images showed huge troop movements, places where equipment was set up, and logistical plans that went far beyond what any exercise would need. A high-ranking official from British Defense Intelligence later said that the movements were unprecedented and that analysts had to work hard to come up with any explanation other than the obvious: these forces were getting ready for war.

Washington got new information that was much more detailed and scary than anything that had come before. Up until now, people thought that Russia might try to formally annex the Donbas region in eastern Ukraine, or, in the worst-case scenario, try to carve out a land corridor through southern Ukraine that would connect the Donbas with Crimea, which is currently occupied by Russia.

Now, signals intelligence picked up by the NSA and Britain's GCHQ, along with satellite images and human intelligence from people inside the Russian system, pointed to something much bigger. Putin wanted to take over Kyiv.

The information was very detailed. Western intelligence reports say that Russian military planners thought that only 10% of Ukrainians would actively fight against the invasion, while the rest would either support or reluctantly accept the Russian takeover. What Moscow's war planners apparently failed to grasp was that even 10 percent of Ukraine's population amounted to roughly four million people — a resistance force that the assembled Russian invasion army, estimated at 150,000 to 200,000 troops, was wholly insufficient to suppress.

"Trust Us": The Desperate Attempt to Convince Kyiv

In late October 2021, the CIA and MI6 sent official letters to Kyiv outlining their new, troubling assessments. Two American officials flew to the capital of Ukraine to meet with senior Ukrainian officials in person. Eric Green, one of the U.S. officials, later said that the meeting was very important: "We made it clear to them that this was not a routine warning and that the situation was very serious." "Believe us."

The Ukrainians were careful. There was a lot of doubt.

Biden stepped up the effort in November. He sent CIA Director William Burns to Moscow to give Putin a direct warning. Burns talked to Putin on the phone because he couldn't meet him in person. Putin had become more paranoid and isolated and had few in-person meetings. He told Putin straight out that the US thought Russia was getting ready to invade Ukraine and that the results would be terrible.

Putin didn't care. Instead of responding to the warning, he changed the subject to his own problems, telling Burns that Russian intelligence had told him that an American warship with missiles that could reach him in minutes was hiding beyond the Black Sea horizon. He said that this showed how vulnerable Russia was strategically in a world where the United States was the only superpower.

When Burns got back to Washington, Biden asked him again if an invasion was likely. There was no doubt in Burns's mind: "I said, 'Yes.'"

Russian troops crossed the border three and a half months later.

Biden also sent Avril Haines, the Director of National Intelligence, to Brussels in November for the annual meeting of the heads of NATO member intelligence services. There, Haines talked about how the U.S. thought a huge Russian invasion was now a real threat. Richard Moore, the head of MI6, spoke out in support of her. Most people in the room, on the other hand, were skeptical. Some people who were there flat out said no.

Biden then told his team to share as much information as possible with allies. This was an unprecedented move to make some findings public while keeping sources and methods secret. The goal was twofold: to keep Moscow from doing anything and to keep allies from being caught off guard.

"You can't make a pig fat on market day": Zelensky's Refusal

In the middle of November, Ben Wallace, the British Secretary of Defense, went to Kyiv and told Zelensky that London now thought it was only a matter of "when," not "if," that Russia would invade. He told the president to get the country ready for war right away. Wallace used a simple English saying to get his point across: "You can't fatten a pig on market day."

It seemed like Zelensky was in denial.

He was elected in 2019 on the promise of working to end the war that Russia started in eastern Ukraine in 2014 through peace talks. By the end of 2021, he no longer thought he could reach an agreement with Putin, but he was afraid that talking about a bigger war in public would make people in Ukraine panic, which could lead to an economic and political crisis that would make the country unstable without Russia having to fire a single shot. Zelensky thought that Putin's plan all along was to use fear as a weapon.

It seems that Andriy Yermak, who is the head of the Presidential Office and Zelensky's closest adviser, played a big part. Several Ukrainian sources say that Yermak saw Russia's military stance as part of a "hybrid gray zone" strategy and was sure that Moscow would not risk a major invasion that would permanently damage its relationship with the West. This assessment made its way up to Zelensky and confirmed his gut feeling that he should downplay the warnings.

Zelensky got more and more angry as American and British officials made more and more public comments about the threat. In November, he sent one of his top security officials on a secret mission to a European capital to tell allied leaders that the threat of war was made up and that the US was trying to pressure Russia. Kyiv made it clear that they wanted the warnings to stop.

A European intelligence official later said that the message from Ukrainian briefings in the months leading up to the invasion was always the same: "Nothing will happen." It's all talk and no action. The worst thing that could happen would be fighting in Donbas.

Berlin, Paris, and the Iraq War

In the capitals of continental Europe, the refusal to heed American warnings stemmed from both strategic considerations and historical grievances.

French and German intelligence agencies did not see the Russian military buildup as a plan for war, but rather as a high-stakes bluff to get Ukraine to back down on its NATO ambitions. In Paris and Berlin, just like in Kyiv, the idea of a full-scale land war in Europe in the 21st century seemed like something from the past.

The ghost of Iraq was very big. European leaders brought up the false intelligence picture that had been used to justify the 2003 invasion over and over again. This was when the US and UK made claims about weapons of mass destruction that turned out to be false. The Iraq war had hurt the credibility of transatlantic intelligence for good, and now, almost twenty years later, European analysts who were skeptical used it as an excuse to ignore what turned out to be a true and urgent warning.

British defense intelligence officials later said that they made "huge efforts" to convince the French and Germans, including sending different delegations on multiple fact-finding trips. At every turn, the talks faced a lot of opposition. Even Poland, which is usually one of NATO's most hawkish members when it comes to Russia, didn't believe in the idea of a full-scale invasion.

Jake Sullivan, Biden's national security adviser, later said, "The evidence we gave them was overwhelming." We didn't hold back anything that would have made a difference if they had seen it. They were sure that the warnings didn't make any sense.

By December 2021, Washington had such a clear picture of Putin's war plan that a "Tiger Team" made up of people from different agencies started meeting three times a week to come up with ways to respond. In the first half of January 2022, even more detailed information came in: Russian troops were going to attack from several places, including Belarus in the north. Airborne troops would take over Hostomel Airport, which is also called Antonov Airport and is only 10 kilometers northwest of Kyiv. This would create an airbridge to bring in more troops to quickly kill the Ukrainian government. Zelensky would be the target of assassination teams. Russian intelligence agencies had even made lists of Ukrainian officials to be arrested or killed, along with pro-Russian figures to be put in charge of a puppet government.

In the middle of January 2022, Burns went to Kyiv in secret to tell Zelensky in person about the latest intelligence. He went into great detail about the planned invasion routes, the air attack on Hostomel, and the goal of taking down the government. Later, Burns told reporters that the intelligence had narrowed its focus to a strike straight across the Belarusian border, which is only a short drive from Kyiv, to take the capital, kill the regime, and put in place a pro-Russian government.

The Last Night: The Generals "Woke Up" and the President Went to Bed

As the last days went by, there was a quiet split in Ukraine's own leadership. Even though Zelensky kept saying the threat wasn't that bad, parts of the military and intelligence community started to take action.

General Valerii Zaluzhny, who is in charge of Ukraine's military, and the HUR, which is the military intelligence directorate, had slowly come to believe that the Americans and British were right. Zaluzhny and his top generals rushed to put emergency plans into action on the night before the invasion. Mines were put on the bottom of the Black Sea to stop a possible Russian landing in Odessa by sea. Some military units were told to move to places that were easier to defend. The HUR kept getting ready in its own quiet way.

But these were last-minute changes, not the result of months of careful planning. On February 20, just four days before the invasion, the National Guard's 4th Rapid Reaction Brigade, which was in charge of protecting the very important Hostomel airfield, sent its best troops to the Luhansk region to fight on the front lines. The airport garrison was left with only a few hundred troops, most of whom were conscripts or administrative staff.

Zelensky's public stance didn't change until the very last minute. He told the presidents of Poland and Lithuania that they might not see him alive again, which showed that he finally understood how serious things were going to get. He tried to call Putin directly later that day. The Kremlin said no to the request.

Later, Zelensky said that he and his wife Olena went to bed like they always do.

The War Starts at 4:50 AM

Putin said at 4:50 a.m. Kyiv time on February 24, 2022, that a "special military operation" was starting. Within minutes, Russia launched a barrage of missile strikes against military bases, air defense positions, and important infrastructure all over Ukraine, including targets in and around the capital.

Around 5:30 a.m., a group of 20 to 34 helicopters, including Mi-8 transport planes carrying elite soldiers from the 31st Guards Air Assault Brigade and 45th Separate Guards Spetsnaz Brigade, flew low over the Kyiv reservoir and headed for Hostomel Airport. They were followed by Ka-52 Alligator attack helicopters. It was the first step in what was supposed to be a quick seizure of the capital. At an airbase in Pskov, Russia, a follow-on force of up to 4,000 soldiers had loaded onto an estimated 41 Il-76 transport planes. They were ready to land at the airport once it was safe and bring in more troops.

When the French ambassador to Ukraine woke up to the sound of Russian missiles, he learned about the invasion. Putin was hosting Pakistani Prime Minister Imran Khan at the Kremlin that same morning. The visit had been planned ahead of time. Putin told Khan not to worry about the war when Khan asked about it. "It will be over in a few weeks."

The Fight That Made Everything Different

Hostomel was the key to the plan for a quick decapitation strike. The airport, which was only 10 kilometers from central Kyiv and had runways that could handle heavy military transport planes, was the key to Russia's entire northern offensive. If it fell quickly, Russian airborne troops would set up an airbridge, armored columns from Belarus would join forces, and the two groups would drive into the heart of the capital within days.

It didn't work out.

Even though they were outnumbered and outgunned, the small Ukrainian garrison, which was mostly made up of conscripts from the National Guard's 4th Rapid Reaction Brigade, fought back with all their might. Ukrainian troops shot down a number of Ka-52 attack helicopters and damaged a number of transport planes. By noon, the first Russian airborne force had taken control of the airport, but it wasn't safe enough for the transport planes to land. Russia called off the Il-76 airlift mission while some planes were already on their way. It's not clear why, but it could have been because the runway was damaged, the helicopter assault force lost 17 to 20 percent of its members, or they couldn't secure the area around it.

The 80th and 95th Air Assault Brigades and the 72nd Mechanized Brigade sent reinforcements to Ukraine and attacked back. After a lot of fighting, the airport was back in Ukrainian hands by nightfall on February 24. Russian ground troops coming from Belarus eventually took it back, but the important time to set up an airbridge had already passed. The plan to take Kyiv in a few days fell through.

People have compared the battle to Operation Market Garden, the failed Allied airborne attack at Arnhem in 1944. However, the attacker at Hostomel would have faced much worse strategic consequences if they had failed. Military experts at West Point and the Center for a New American Security have said that it was one of the most important military conflicts of the 21st century. If Russia had taken and held the airport even a few hours earlier, the war might have ended in its first few days.

The Intelligence Reckoning

The European intelligence services that were so sure there would be no invasion had to face an uncomfortable truth. Looking back, their explanation had a darkly ironic quality. "We didn't think it would happen because we thought the idea that they could just walk into Kyiv and set up a puppet government was completely crazy," said one European intelligence official. It turned out that it was completely crazy.

They were right that the plan was crazy, but they were wrong to think that its craziness would stop it from happening. This was the main analytical mistake: thinking that Putin wouldn't go through with the plan because it didn't make sense strategically.

The CIA and MI6 both had things they couldn't see. They correctly identified the invasion's scope, timing, and purpose, but they greatly overestimated the effectiveness of the Russian military and underestimated the strength of the Ukrainian resistance. Washington thought that Putin would win at first: that Russian troops would take Kyiv in a matter of weeks, and then Ukraine would regroup for a longer fight. Later, Director of National Intelligence Haines admitted that they had made a mistake. "We thought the Russians would be better at first—they would take Kyiv in a couple of weeks, and then the Ukrainians would regroup."

No one in the Western intelligence community fully expected the combination of Russian incompetence, Ukrainian resilience, and the game-changing effect of Zelensky's choice to stay in Kyiv instead of fleeing. The man who had been in denial for months became a wartime leader of defiance overnight, rallying both his country and the world.

Lessons for a World That Isn't Sure

Four years later, the intelligence story of the Ukraine invasion has lessons that go beyond the details of the Russo-Ukrainian conflict. The Guardian investigation and the larger academic study it has led to point to a few truths that will last.

First, intelligence is only useful if the people who make decisions are willing to act on it. The CIA and MI6 put together one of the most detailed and accurate threat pictures in modern intelligence history, but it was mostly useless because important leaders in Kyiv, Berlin, Paris, and other places refused to believe what it was telling them.

Second, the shadow of past failures can be just as dangerous as the failures themselves. The Iraq intelligence disaster made people doubt American assessments, and two decades later, Europe was almost completely unprepared for the biggest military attack on its soil since World War II.

Third, rational actor models have some limits. Thinking that a leader won't do something because it seems strategically stupid is a kind of analytical failure in and of itself. Putin's choice to invade was influenced by ideology, isolation, historical fixation, and a severely skewed intelligence assessment from his own agencies—elements that do not align with Western rational decision-making frameworks.

Finally, the quality of intelligence analysis depends on more than just the information that is gathered. It also depends on the courage to accept conclusions that are not easy to accept. Many experts say that the world is now in the most unstable geopolitical period since the Cold War. The fact that people didn't listen to the warnings before February 24, 2022, is a warning that the most dangerous situations are often the ones that seem the least likely to happen.

About 400,000 Russian soldiers have died in the war. The war that Putin said would end in weeks is still going on after four years. The information was correct. The sad thing is that it wasn't enough.