Russian President Vladimir Putin’s seizure of the Crimean Peninsula from Ukraine in early 2014 was the most consequential decision of his 16 years in power. By annexing a neighboring country’s territory by force, Putin overturned in a single stroke the assumptions on which the post–Cold War European order had rested.

The question of why Putin took this step is of more than historical interest. Understanding his motives for occupying and annexing Crimea is crucial to assessing whether he will make similar choices in the future—for example, sending troops to “liberate” ethnic Russians in the Baltic states—just as it is key to determining what measures the West might take to deter such actions.

Three plausible interpretations of Putin’s move have emerged. The first—call it “Putin as defender”—is that the Crimean operation was a response to the threat of NATO’s further expansion along Russia’s western border. By this logic, Putin seized the peninsula to prevent two dangerous possibilities: first, that Ukraine’s new government might join NATO, and second, that Kiev might evict Russia’s Black Sea Fleet from its long-standing base in Sevastopol.

A second interpretation—call it “Putin as imperialist”—casts the annexation of Crimea as part of a Russian project to gradually recapture the former territories of the Soviet Union. Putin never accepted the loss of Russian prestige that followed the end of the Cold War, this argument suggests, and he is determined to restore it, in part by expanding Russia’s borders.

A third explanation—“Putin as improviser”—rejects such broader designs and presents the annexation as a hastily conceived response to the unforeseen fall of Ukrainian President Viktor Yanukovych. The occupation and annexation of Crimea, in this view, was an impulsive decision that Putin stumbled into rather than the careful move of a strategist with geopolitical ambitions.

Over the past two years, Putin has appeared to lend support to all three interpretations. He has suggested that Ukraine’s accession to NATO would have been intolerable and has also claimed that Crimea’s history had made the region “an inseparable part of Russia,” “plundered” from the country after the Soviet Union’s disintegration. Yet Putin also told me, at a reception in Sochi in October 2015, that the operation to seize the peninsula was “spontaneous” and was “not at all” planned long in advance. (Putin’s other explanations for the intervention—that he ordered it to protect Crimea’s Russian population from Ukrainian nationalists and to respect Crimeans’ right to self-determination—should be taken less seriously, since the nationalist threat in Crimea was largely invented and since Putin had shown little interest in self-determination for the peninsula for most of his previous 14 years in power.)

So what was the annexation—a reaction to NATO’s expansion, an act of imperial aggression, or an impromptu response to an unexpected crisis? The truth might involve elements of more than one theory, and some of the details remain unknown. Nevertheless, information that has surfaced over the past two years and insights from recent interviews in Moscow suggest some important conclusions: Putin’s seizure of Crimea appears to have been an improvised gambit, developed under pressure, that was triggered by the fear of losing Russia’s strategically important naval base in Sevastopol.

NATO’s enlargement remains a sore point for Russian leaders, and some in the Kremlin certainly dream of restoring Russia’s lost grandeur. Yet the chaotic manner in which the operation in Crimea unfolded belies any concerted plan for territorial revanche. Although this might at first seem reassuring, it in fact pre­sents a formidable challenge to Western officials: in Putin, they must confront a leader who is increasingly prone to risky gambles and to grabbing short-run tactical advantages with little apparent concern for long-term strategy.

A Russian serviceman stands behind a wall on which the Ukrainian national flag is painted at the Belbek Sevastopol International Airport in Crimea, March 2014. Vasily Fedosenko / REUTERS

NATO NYET!

Consider first the notion that Putin ordered the seizure of Crimea to prevent Russia’s military encirclement by NATO. It is clear that enlarging NATO without making more than token attempts to integrate Russia helped poison the relationship between Moscow and the West over the past two decades, just as it is well known that Russia’s leaders are determined to prevent Ukraine from becoming a NATO member. But that does not mean that resisting NATO’s expansion was what motivated Putin in this case.

The biggest problem with the theory that Putin seized Crimea to stop Ukraine from joining NATO is that Ukraine was not heading toward NATO membership when Putin struck. In 2010, in large part to improve relations with Russia, the Yanukovych government had passed a law barring Ukraine from participation in any military bloc. In subsequent years, Kiev settled instead for partnership with the alliance, participating in some of its military exercises and contributing a ship to NATO antipiracy operations—an outcome that Russia seemed to accept. Indeed, when Putin, justifying the intervention in March 2014, claimed that he had “heard declarations from Kiev about Ukraine soon joining NATO,” he excluded an important detail: all the recent public statements to that effect by Ukrainian politicians had come only after Russian troops had already appeared in Crimea.

Even if Ukrainian officials had wanted to join NATO after Yanukovych’s ouster, the alliance was not about to let the country in. Putin had already won that battle at a NATO summit in 2008, when the alliance had chosen not to move forward on Ukrainian or Georgian membership. British, French, and German officials had argued that the two countries remained too unstable to be put on a path to joining the alliance and that doing so would also unnecessarily antagonize Moscow. Although NATO did not rule out Ukraine’s eventual accession, German Chancellor Angela Merkel remained opposed to practical steps in that direction, and U.S. President Barack Obama, unlike his predecessor, George W. Bush, took no action to advance Kiev’s membership. What is more, in October 2013, just months before Russia’s annexation of Crimea, Anders Fogh Rasmussen, NATO’s secretary-general, announced unequivocally that Ukraine would not join the alliance in 2014. There was little reason to expect that to change anytime soon.

Putin’s seizure of Crimea appears to have been an improvised gambit, developed under pressure.

Of course, Putin might have believed otherwise. If that were the case, however, he would probably have raised the issue with Western leaders. He seems not to have done so, at least not with Obama, according to Michael McFaul, who served as the president’s special assistant on Russia from 2009 to 2012 and as the U.S. ambassador in Moscow from 2012 to early 2014. During that period, McFaul was present for all but one of the meetings between Obama and Putin or Dmitry Medvedev, who served as Russia’s president from 2008 to 2012; while he was serving in Washington, McFaul also listened in on all the phone conversations Obama had with either Russian leader. In a speech last year, McFaul said he couldn’t “recall once that the issue of NATO expansion came up” during any of those exchanges.

If Putin’s goal was to prevent Russia’s military encirclement, his aggression in Ukraine has been a tremendous failure, since it has produced exactly the opposite outcome. Largely to deter what it perceives as an increased Russian threat, NATO has deepened its presence in eastern Europe since Moscow’s intervention, creating a rapid-reaction force of 4,000 troops that will rotate among Bulgaria, Estonia, Latvia, Lithuania, Poland, and Romania and stationing four warships in the Black Sea. In February, the White House revealed plans to more than quadruple U.S. military spending in Europe.

Last January, I asked a source close to Oleg Belaventsev, the commander of Russia’s military operation in Crimea, if Russian officials had been worried about Ukraine joining NATO in the months preceding the intervention. “They weren’t afraid of Ukraine joining NATO,” the source replied. “But they were definitely worried that the Ukrainians would cancel the [Russian] lease on [the naval base in] Sevastopol and kick out the Black Sea Fleet.”

This seems plausible, since the Black Sea Fleet is crucial to Russia’s ability to project force into the Black and Mediterranean Seas and since many of Ukraine’s opposition leaders had criticized Yanukovych for extending Moscow’s lease on the base. Yet if securing the base was Putin’s main concern, as seems likely, the puzzle is why he chose such a risky strategy. With a contingent of around 20,000 well-armed troops in Crimea and a mostly pro-Russian population on the peninsula, it would have been difficult for Ukraine to evict Russia from Sevastopol, and in the past, Moscow had always found ways to protect its interests in the region without using force. Annexing the territory—at the cost of international isolation, economic sanctions, the reinvigoration of NATO, and the alienation of most of the Ukrainian population—seems like an extreme reaction to a manageable threat. Before the operation in Crimea, Putin’s decisions could generally be rationalized in terms of costs and benefits, but since then, his foreign policy calculus has been harder to decipher.

IMPERIAL DELUSIONS?

For those who see Putin as an imperialist, Russia’s moves in Crimea are easy to explain. After all, Putin has notoriously characterized the collapse of the Soviet Union as “the greatest geopolitical catastrophe of the century,” has claimed that “Ukraine is not even a state,” and has a history of meddling in countries on Russia’s periphery. In 2008, the same year that Russian tanks rolled into Georgia to protect the separatist enclaves of Abkhazia and South Ossetia, Russian officials were reportedly distributing Russian passports to Crimean residents, creating an apparent pretext for an invasion in their defense.

Other, more specific signs also seem to show that Moscow was preparing to seize Crimea in the six months before Yanukovych’s fall. Vladislav Surkov, a senior Putin adviser, repeatedly visited Kiev and Simferopol, the Crimean capital, in the fall and winter of 2013–14, in part to promote the construction of a bridge across the Kerch Strait to connect southern Russia and Crimea—an essential transportation link in case of annexation. Around the same time, teams of Russian police and secret service officers were seen in Kiev.

Meanwhile, Vladimir Konstantinov, the chair of the Crimean parliament, was making frequent trips to Moscow. On one such visit, in December 2013, according to the Russian journalist Mikhail Zygar, he met with Nikolai Patrushev, the secretary of Russia’s Security Council and the Kremlin’s top security official. According to Zygar’s report, Patrushev was “pleasantly surprised” to learn from Konstantinov that Crimea would be ready to “go to Russia” if Yanukovych were overthrown. Just before Russia’s intervention, Konstantinov was back in Moscow, meeting with senior officials.

Russian President Vladimir Putin, Crimean Prime Minister Sergei Aksyonov, Vladimir Konstantinov, and Sevastopol Mayor Alexei Chaliy at a treaty-signing ceremony in Moscow, March 2014. Sergei Ilnitsky / Pool / REUTERS

Other evidence also suggests a long-standing Russian plot to acquire the peninsula. In February 2014, according to the newspaper Novaya Gazeta, a memo circulated in Russia’s executive branch proposing the annexation of Crimea and other parts of eastern Ukraine if Yanukovych fell. With Yanukovych gone, the memo suggested, Ukraine would split into western and eastern parts, and the EU would swallow up the west. Moscow would need to quickly promote referendums on the issue of Russian annexation in the pro-Russian regions in the country’s east.

Yet on closer examination, the theory that Putin had long intended to take Crimea doesn’t quite hold up. Consider Surkov’s frequent trips to the peninsula. What the Putin adviser discussed with local leaders on these visits remains unknown. If Surkov was preparing for the region’s annexation, however, Putin’s next move seems bizarre. Instead of sending Surkov to Simferopol to oversee Russia’s intervention, Putin took him off the case in late February; Surkov apparently spent most of March in Moscow, with enough free time to attend a gallery opening and even take a vacation in Sweden with his wife. Zygar has suggested that Surkov’s real assignment in Ukraine had been not to prepare for the annexation of Crimea but to keep Yanukovych in power—a task at which he failed, much to Putin’s displeasure. As for the police and secret service teams seen around Kiev, their role was likely to advise Yanukovych’s staff on how to crush antigovernment protests in the capital; had they been planning for an operation in Crimea, they would have been sent there instead.

Indeed, many details that at first seem to indicate careful Russian preparation actually point to the absence of any long-held plan. For example, if Moscow had really been scheming to annex Crimea, it would not have merely discussed a bridge over the Kerch Strait with Ukrainian officials; it would have built one. Instead, the negotiations had crept along for more than ten years, and between 2010, when Yanukovych and Medvedev agreed to build the bridge, and 2014, Russia did not even manage to complete a feasibility study for the project.

If Moscow had really been scheming to annex Crimea, it would not have merely discussed a bridge over the Kerch Strait; it would have built one.

That a document as speculative as the pro-annexation memo revealed by Novaya Gazeta was circulating less than a month before the operation, meanwhile, suggests that Putin had not adopted a concrete plan by February 2014. And why was Patrushev, a senior official and reportedly one of the strongest backers of intervention in Ukraine, “surprised” to hear that the Crimean elite would approve of annexation? If the Kremlin had been contemplating an occupation, Patrushev would have seen intelligence reports to that effect by the time of his meeting with Konstantinov in December 2013.

In fact, until shortly before it happened, it appears that Putin did not expect Yanukovych to fall from power. If he had, he likely would have found some pretext to postpone the disbursement of a $3 billion loan that Russia had promised the Yanukovych government in December 2013. He didn’t, of course, and Ukraine’s new government defaulted on the loan in December 2015. As the political consultant and former Kremlin official Aleksei Chesnakov told me, “It’s not Putin’s style to make such presents.”

WINGING IT

The clearest evidence against a consistent plan for territorial expansion is the chaotic way in which the Crimean intervention unfolded. Although the military component of the operation ran smoothly, its political aspects at times revealed an almost farcical lack of preparation.

Putin has said that he first instructed aides to “start working on returning Crimea to Russia” on the morning of February 23, after Yanukovych fled Kiev. In fact, according to the source close to Belaventsev, the commander of the Crimean operation, Moscow put Russian special forces in the southern port city of Novorossiysk and at the Black Sea Fleet’s base in Sevastopol on alert on February 18, as violence flared up between police and antigovernment protesters in Kiev. Two days later, on February 20, Russian troops received an order from Putin to blockade Ukrainian military installations in Crimea and prevent bloodshed between pro-Russian and pro-Kiev groups protesting on the peninsula. But they did not begin to do so until February 23, two days after Yanukovych left Kiev. The earliest steps in the operation, in other words, appear to have been tentative: Putin could have called off the mission if the agreement that Yanukovych signed with opposition leaders and EU foreign ministers on February 21 to hold early elections had stuck.

Belaventsev arrived in Crimea on February 22, according to the source. A longtime aide to Russian Defense Minister Sergei Shoigu, Belaventsev was unfamiliar with Crimea’s political scene, and after consulting locals, he persuaded the incumbent prime minister, an unpopular Yanukovych appointee, to step down. To replace him, Belaventsev chose an elderly Communist, Leonid Grach, who had been known in Moscow since the Soviet era.

What Belaventsev didn’t know was that Grach had alienated most of Crimea’s power brokers over the years—an oversight that Konstantinov, the leader of the Crimean parliament, made clear to Belaventsev after he had already offered Grach the position. To his embarrassment, Belaventsev had to call Grach to rescind the offer of the premiership only a day after he had made it. To head the regional government, Belaventsev then turned to Sergei Aksyonov, a local pro-Russian businessman and former boxer known to locals by the underworld nickname “Goblin.”

Even more surprising, in the days that followed, the Kremlin appeared not to know what it wanted to do with Crimea. On February 27, the region’s parliament voted to hold a referendum on May 25 to ask residents whether they agreed that Crimea was “a self-sufficient state and . . . is part of Ukraine on the basis of treaties and agreements”—in other words, whether they thought that the region should have greater autonomy but remain in Ukraine. A week after the beginning of the operation, Putin had not yet decided on annexation.

On March 1, Crimea’s parliament rescheduled the referendum from May 25 to March 30. Then, on March 6, the deputies advanced the date by another two weeks, and this time they rewrote the referendum question to ask whether residents supported the unification of Crimea with Russia instead of whether they supported autonomy within Ukraine.

If Putin’s goal was to prevent Russia’s military encirclement, his aggression in Ukraine has been a tremendous failure.

Why did Putin raise the referendum’s stakes from autonomy to annexation? One reason was pressure from pro-Russian Crimean leaders, including Konstantinov, who feared ending up in a semi-recognized statelet like Abkhazia or South Ossetia, shunned by Ukraine and the West and too small to thrive economically. More important, having deployed Russian forces throughout the peninsula, Putin found himself trapped. To simply withdraw, allowing Ukrainian troops to retake Crimea and prosecute Moscow’s supporters there, would have made him look intolerably weak, and after the return of Ukrainian control, Kiev might well have canceled Russia’s lease on the naval base in Sevastopol. The only way Russia could have safely pulled out of Crimea would have been if the West had recognized an eventual vote for Crimean autonomy as legitimate and persuaded the Ukrainian government to respect it. Western leaders, outraged by Russia’s invasion, had made clear that they would do nothing of the sort.

For Moscow to back mere autonomy for the peninsula without Western support would have been dangerous, since Russia would have had to defend Crimea’s pro-Russian government against any attempt by Kiev to use the 22,000 Ukrainian troops stationed there to restore order. If, by contrast, Russia had chosen to expel the Ukrainian forces and defend the region against a counter­offensive, it would have aroused nearly as much hostility in the West as it would if it took control of the territory outright. By March 4, unable to find a viable exit strategy, the Kremlin had decided on annexation.

ON S’ENGAGE, ET PUIS . . .

All this improvisation makes it hard to see Russia’s intervention in Crimea as part of a systematic expansionist project. Any halfway competent imperialist would have known whom to appoint as the local satrap after the invasion and would already have chosen whether to offer residents a referendum on autonomy or annexation. And a resolute revanchist would have made sure to build a bridge to the target territory, rather than squandering ten years in fruitless discussions.

This is not to say there are not factions in the Kremlin with imperial appetites. Putin himself may share such impulses. It is likewise true that Russia’s leaders detest NATO’s enlargement and exploit it as a rhetorical rallying point. Yet such appetites and concerns had not jelled into any coherent plan for an invasion of Crimea. Until shortly before Putin’s commandos struck, the Kremlin had been preoccupied with events in Kiev.

If Putin’s main concern was Moscow’s hold on Sevastopol, this suggests several important points. First, the disastrous turn in relations between Russia and the West over the past two years might have been avoided had Ukrainian officials, as well as opposition leaders and their Western backers, consistently promised to respect the agreement that extended Russia’s lease on the base until the 2040s. To be sure, this agreement was highly unpopular in Ukraine. But had Ukrainians known that the alternative would be the loss of Crimea and a bloody war in the country’s east, they might have settled for the indignity of hosting a foreign power’s forces.

Next, it suggests that Putin has become willing in recent years to take major strategic risks to counter seemingly limited and manageable threats to Russian interests. By deploying special forces in Crimea without planning for the region’s political future, Putin showed that he is not just an improviser but also a gambler. Indeed, encouraged by the high domestic approval ratings his venture secured, Putin has continued to roll the dice, supporting the pro-Russian separatists in Donetsk and Luhansk, bombing antigovernment rebels in Syria, and escalating a confrontation with Turkey over the downing of a Russian warplane in November.

The importance of Sevastopol in the case of Russia’s intervention in Crimea demonstrates the need to accurately identify Russia’s key strategic assets, as seen by Putin, if the West is to anticipate his moves in future crises. The Baltic states contain no Russian bases that might invite a similar intervention. In Syria, the port of Tartus—Russia’s only naval outpost in the Mediterranean—is probably too small and poorly equipped to matter much, although the Russian military might have plans to expand it. A greater threat could arise were Turkey to attempt to close the Turkish Straits, which connect the Black and Mediterranean Seas, to Russian ships. Under the 1936 Montreux Convention, Turkey has the right to deny passage through these straits to military vessels from countries with which it is at war or in imminent danger of conflict. Were Ankara to take this step, it would make it much harder for Russia to provide naval support to military operations in the Mediterranean and the Middle East, such as its recent intervention in Syria, and that might provoke a furious and possibly disproportionate Russian response. That both Putin and Turkish President Recep Tayyip Erdogan need to appear strong internationally for domestic political reasons renders the antagonism between them alarming, so Western leaders should make clear to Ankara that they would not support closing the straits if Russian-Turkish tensions rose further.

Putin’s recent penchant for high-stakes wagers may prove even harder for Western leaders to handle than a policy of consistent expansionism. A rational imperialist can be contained, but the appropriate response to a gambler who makes snap decisions based on short-term factors is less clear. In both Crimea and Syria, Putin has sought to exploit surprise, moving fast to change facts on the ground before the West could stop him. By reacting boldly to crises, he creates new ones for Russia and the world.