BRUSSELS — The European Union officially made Ukraine a candidate for membership on Thursday, signaling in the face of a devastating Russian military onslaught that it sees Ukraine’s future as lying in an embrace of the democratic West.
While Ukraine’s accession into the bloc could take a decade or more, the decision sends a powerful message of solidarity to Kyiv and a rebuke to President Vladimir V. Putin of Russia, who has worked for years to keep Ukraine from building Western ties.
Before Mr. Putin launched the invasion in February, insisting that Ukraine rightly belonged in Russia’s orbit, E.U. leaders would not have seriously considered starting Ukraine, with its history of oligarchy and corruption, on the path to membership.
The decision came at a critical moment in the war, as Russia threatens to capture more territory in eastern Ukraine, where Ukrainian forces are outgunned and at risk of being encircled in fierce combat around the city of Lysychansk.
The leaders of the 27 E.U. nations, meeting Thursday in Brussels, also granted candidate status to Ukraine’s southwestern neighbor, Moldova, spurred by concerns over Russia’s aggression in the region. Both countries, former Soviet republics, face difficult paths to membership in the bloc that will require them to reform their political and economic systems, strengthen the rule of law and fight corruption.
President Volodymyr Zelensky of Ukraine called the E.U. move “one of the most important decisions for Ukraine” in its 30 years as an independent state.
“This is the greatest step toward strengthening Europe that could be taken right now, in our time, and precisely in the context of the Russian war, which is testing our ability to preserve freedom and unity,” Mr. Zelensky wrote on Telegram.
Ukraine’s foreign minister, Dmytro Kuleba, said in an interview that the decision to grant Ukraine’s candidacy showed that the bloc was “overcoming the last psychological barrier in the relations between Ukraine and the European Union.”
He said he was not concerned about how long it might take for Ukraine to join the European Union, which he likened to a “liberal empire” that is expanding as the “Russian empire is shrinking.”
“It may take a year. It may take a decade,” Mr. Kuleba said. “But 10 years ago, in the perception of the European elite, we were still a part of the Russian world.”
The prospect of European Union membership has been overshadowed in Ukraine by the daily brutality of the invasion. Russian forces are hammering the last pocket of resistance in the eastern Luhansk Province, where an intensifying battle appears to put Ukrainian troops at risk of their greatest losses since the fall of Mariupol a month ago.
On Thursday, Russian forces pounded Ukrainian supply lines into that pocket. Yet there was no sign of a broad retreat by Ukraine’s forces, as a Ukrainian fighter jet screamed through the sky and troops dug into defensive positions.
Better Understand the Russia-Ukraine War
Amid the fierce fighting, Ukraine’s defense chief hailed the arrival of advanced artillery rocket launcher systems from the United States, the latest in a cache of powerful weapons from the West. But it remains unclear if the relatively small number of the HIMARS rocket artillery systems sent by the Pentagon will shift the battlefield dynamic.
The White House on Thursday authorized $450 million in new military aid to Ukraine, in addition to billions delivered already this year, including four more HIMARS launchers, 1,200 grenade launchers, 2,000 machine guns and 18 patrol boats, the Pentagon said.
The Ukrainian military high command said that Moscow was continuing to add men and armor in the fight to capture Lysychansk and finish off the Ukrainian resistance in nearby Sievierodonetsk. The cities lie on either side of the Siversky Donets River.
On Thursday, shelling near the supply lines that run toward Lysychansk was incessant. Ukrainian rocket launchers, their tubes loaded, waited to move into position or sped toward the front. What appeared to be two cruise missiles also hit Bakhmut, about 30 miles to the southwest, a supply hub for Ukrainians, sending mushroom-shaped clouds of smoke into the air.
Military analysts said that the stubborn Ukrainian defense has severely depleted Russia’s fighting force. But Ukraine has also absorbed heavy losses and has turned to undertrained troops as reinforcements.
Likening the two armies to boxers exhausted after 18 rounds, an adviser to Mr. Zelensky said the battle was reaching its “fearsome climax.”
“The threat of a tactical Russian victory is there, but they haven’t done it yet,” the adviser, Oleksiy Arestovich, said on national television.
Making Ukraine a candidate for European Union membership will have no immediate effect on the fight, and merely starts an uncertain process toward accession. Turkey has been a candidate since 1999 and North Macedonia since 2005, and both have yet to join the bloc. In a system that works by consensus, any nation effectively has a veto over new members.
Yet the decision was bound to irritate Mr. Putin, who has had a charged and vexing relationship with the European Union — and with the desire by a growing numbers of Ukrainians to join it.
Asked last week about Ukraine’s looming candidate status, Mr. Putin sounded uncharacteristically subdued. “We have no objections,” he said.
But since then, Russian officials have sent much sharper signals.
“We consider the E.U. enlargement process to be negative — hostile, in fact — in relation to Russian national interests,” Russia’s ambassador to the bloc, Vladimir A. Chizhov, told a state-run newspaper this week.
In fact, Ukraine’s desire to draw closer to the European Union helped set off nearly a decade of conflict. In 2013, a Kremlin-backed president of Ukraine, Viktor F. Yanukovych, was on the verge of signing a popular E.U. trade deal when he reneged under pressure from Mr. Putin. Mass pro-Western protests ensued, toppling Mr. Yanukovych, and Mr. Putin responded by seizing Crimea from Ukraine and fomenting a separatist insurgency that took control of parts of the eastern Donbas region.
The Kremlin has argued that Ukraine’s membership bid is the product of an anti-Russian alliance between Washington and London that has been pushing the effort against the European Union’s best interests — a view that European leaders dismiss as absurd.
Russian officials have also depicted the expansion of the European Union as a twin threat alongside the expansion of NATO. The rationale Mr. Putin and his circle have offered for going to war leans heavily on unfounded claims that NATO was moving into Ukraine.
Mr. Chizhov, the Russian ambassador, told the Izvestia newspaper that the European Union “lately has degraded to the level of an auxiliary military bloc, auxiliary to NATO.”
For Russians and Ukrainians alike, the question of whether Ukraine will someday join the European Union is secondary to the more immediate question of how the country survives the Russian invasion. That may be one reason Ukraine’s membership bid has not been a top news story in Russia.
“There’s a point of view that Ukraine either won’t exist, or won’t exist in its current geographic boundaries,” said Andrei Kortunov, director general of the Russian International Affairs Council, a research organization close to the Russian government, describing the view in Moscow. “This sense even further reduces the significance of the decision on candidate status. Because everything can change.”
Russia is also using its vast energy resources to inflict economic pain on Ukraine’s European allies.
A week after Russia’s state energy giant, Gazprom, reduced its natural gas deliveries to Germany by 60 percent, Germany triggered the second stage of its three-step emergency gas plan on Thursday, warning that it was in a crisis that could worsen in coming months.
“The situation is serious and winter will come,” Robert Habeck, Germany’s economy minister, said at a news conference in Berlin. The plan’s third step would permit the government to begin gas rationing.
“Even if you don’t feel it yet: We are in a gas crisis,” he said. “Gas is a scarce commodity from now on. Prices are already high and we have to be prepared for further increases. This will affect industrial production and become a big burden for many consumers.”
Mr. Habeck called Gazprom’s cutbacks a deliberate economic attack by Mr. Putin.
“It is obviously Putin’s strategy,” he said, “to create insecurity, drive up prices and divide us as a society.”
Matina Stevis-Gridneff reported from Brussels, Thomas Gibbons-Neff from Bakhmut, Ukraine, and Michael Levenson from New York. Reporting was contributed by Natalia Yermak from Bakhmut, Valerie Hopkins from Kyiv, Anton Troianovski and Melissa Eddy from Berlin, John Ismay from Washington, Marc Santora from Warsaw and Monika Pronczuk from Brussels.
