In September, 1949, two Ukrainian agents working with the C.I.A. landed near Lviv, in what was then the Soviet Union. They were the vanguard of an operation that would acquire the code name Redsox. Its aim was to connect with anti-Soviet insurgents fighting by the tens of thousands in Ukraine, as well as in smaller numbers elsewhere on Russia’s rim. Soviet moles betrayed the program, however, and at least three-quarters of the Redsox agents disappeared. By the mid-nineteen-fifties, Moscow had quelled Ukraine’s rebellion while forcibly displacing or killing hundreds of thousands of people. The C.I.A.’s glancing intervention was “ill-fated and tragic,” an internal history concluded.

Since Vladimir Putin ordered Russia’s unprovoked invasion of Ukraine, on February 24th, the United States has acted as if to redeem itself; the Biden Administration has led its NATO allies to airlift planeloads of Javelin anti-tank weapons and Stinger anti-aircraft missiles to Ukrainian forces, while pledging billions of dollars more in military assistance and imposing punishing sanctions on Russia’s economy and Putin’s élite. More than three weeks after the crisis began, the mood in Western capitals remains pugnacious and emotive. Last week, the Ukrainian President, Volodymyr Zelensky, appeared by video before Canada’s Parliament, and, the next day, he addressed a joint session of Congress. In both venues, politicians rose to applaud and chanted an improbably viral invocation of Ukrainian glory: “Slava Ukraini! ”

Yet NATO has declined to provide Ukraine what Zelensky has repeatedly sought—a no-fly zone to ground Russian warplanes or a transfer of fighter jets—for fear that such actions would bring the U.S. and Russia into direct combat. “We will not fight a war against Russia in Ukraine,” Joe Biden reiterated on Twitter recently. “A direct confrontation between NATO and Russia is World War III. And something we must strive to prevent.” The President is, of course, right about that, and yet, as Russian planes and artillery daily pound Ukrainian apartment buildings and hospitals, he can surely understand why Zelensky is pressing for more.

Zelensky has been justly celebrated for his personal courage and his adaptations of Churchillian rhetoric for the TikTok era. His presentation to Congress last week was a study in discomforting moral provocation. He invoked Pearl Harbor and September 11th to describe Ukraine’s daily experience under Russian missiles and bombs, then showed a graphic video depicting the recent deaths of children and other innocents. Later that day, Biden called Putin “a war criminal” and announced a new package of military supplies, including anti-aircraft systems and drones. The aid may help, but it cannot relieve Zelensky of the terrible predicaments he must manage in the weeks ahead. Ukraine may be facing a long war costing the lives of hundreds of thousands of its citizens, a war that may not be winnable, even with the most robust assistance that NATO is likely to provide. In any event, NATO’s greatest priority is to strengthen its own defenses and dissuade Putin from attacking the alliance.

Zelensky’s alternative may be to pursue a ceasefire deal with Putin that could require Ukraine to forswear future NATO membership, among other bitter concessions. In the light of Putin’s annexation of Crimea, in 2014, and his years-long armed support for pro-Russian enclaves in Ukraine’s east, such a deal would be unstable and unreliable. Still, Zelensky appears torn. Even as he asked Congress last week to “do more” for Ukraine’s war effort, he pleaded with Biden to lead the world to peace, and he recently signalled his willingness to bargain with Putin on Ukraine’s relationship with nato. The country’s past failure to win admission to the alliance is “a truth” that “must be recognized,” he said.

It has become common to describe Russia’s invasion as a watershed in history comparable to 9/11 or to the fall of the Berlin Wall. “The war in Ukraine marks a turning point for our continent and our generation,” President Emmanuel Macron, of France, said earlier this month. Perhaps, but some of this speculation about Europe’s destiny and the future of Great Power competition may be premature. Certainly, the war has already produced a humanitarian disaster of shocking and destabilizing dimensions. Three million Ukrainians have fled their country. The 1.8 million of them who have gone to Poland constitute a population roughly the size of Warsaw’s. If the fighting drags on and Ukraine implodes, the country will export many more destitute people, and, as happened in the former Yugoslavia during the nineteen-nineties, it may also draw in opportunists, including mercenaries and extremists.

Meanwhile, Russia’s economy, according to the International Monetary Fund, could shrink by thirty-five per cent this year under the weight of Western sanctions. Putin’s oligarchs and enablers can endure the loss of super-yachts and private jets, but a sudden economic contraction on that scale would crush ordinary Russians and inevitably cost lives. (“Our economy will need deep structural changes,” Putin acknowledged last week, adding, “They won’t be easy.”) Russia’s isolation from large swaths of global banking and trade, and its loss of access to advanced U.S. technologies, could last a long time, too: democracies often find it easier to impose sanctions than to remove them, even when the original cause of a conflict subsides. (Ask Cuba.) “When the history of this era is written, Putin’s war on Ukraine will have left Russia weaker and the rest of the world stronger,” Biden said in his recent State of the Union address.

Still, some introspection may be in order. In his address, the President also declared that, “in the battle between democracy and autocracies, democracies are rising to the moment.” But Europe is troubled by illiberal populism, including in Poland. And Donald Trump—who, just two days before Russia rolled into Ukraine, called Putin’s preparatory moves “genius”—retains a firm hold on the Republican Party, and appears to be all in for a reëlection campaign in 2024. As long as Trump’s return to the White House is a possibility, Biden’s declarations will require some asterisks.

“Every night for three weeks now,” Zelensky told Congress, “various Ukrainian cities, Odessa and Kharkiv, Chernihiv and Sumy, Zhytomyr and Lviv, Mariupol and Dnipro,” have endured attacks. “We are asking for a reply, for an answer to this terror.” Ukraine is an unlucky country, and the restoration of its independence and security may be a long and costly project, but it is one the U.S. cannot afford to abandon again. ♦