Assessments that Ukraine has reached a turning point in the conflict with Russia may well prove premature. But the towering dome of black smoke that hung over Moscow this week after a Ukrainian drone onslaught showed that Kyiv still has plenty of cards to play, no matter President Trump’s earlier appraisal of its prospects in the war.

President Volodymyr Zelensky’s hand was made clear as he moved to seize the initiative both militarily and diplomatically.

The strikes on Moscow left part of the city’s biggest oil refinery in flames. An immense blast sent the top of a fuel storage vessel soaring into the air — and blew the roof off the idea that Russia could continue to shield Muscovites from the war.

At the same time, Mr. Zelensky was securing a statement of “unwavering support” from the Group of 7 industrialized nations during a summit in France. It was a rare unified expression of backing for Kyiv that came even after Mr. Trump signaled at the summit that ending the war was no longer among his top priorities, saying that the United States had “nothing to do” with the conflict.

The remark by Mr. Trump, who has been seen as favoring Russia in peace negotiations, may actually have been a source of relief for European officials who have discussed taking a more active role in trying to halt the war.

The G7 delivered its message of support just as negotiations officially began for Ukraine to join the European Union. By Thursday, as part of Moscow burned, the bloc reaffirmed that a loan to Ukraine of 90 billion euros ($103 billion) approved in December would begin to be disbursed this month. The country’s defense minister also announced $4 billion in new pledges of Western military aid.

It is far from clear that Ukraine’s expanding campaign of long-range strikes on Russia and its solidified support from European allies will push the war closer to a conclusion.

But this week’s developments reinforced a growing sense of confidence in Kyiv that it would be able to force the Russian president, Vladimir V. Putin, to the negotiating table, even as Russia continues to pound the Ukrainian capital with missiles and drones, exploiting Ukraine’s air defense shortage.

“Ukraine is strong — everyone absolutely agrees on that,” Mr. Zelensky told journalists in a voice message late Thursday. “Putin does not want to stop. And everything he says about wanting peace is a lie. All partners, all Europeans, feel this. But they are also convinced that together we will stop him. The key is ‘together’ and ‘we will.’”

European leaders reiterated his view as they wrapped up the meetings that secured more backing for Ukraine.

“The tide is clearly turning for Ukraine,” Ursula von der Leyen, the president of the European Commission, said on Thursday. “The momentum is strong. And Europe will carry it even further.”

The Lithuanian president, Gitanas Nauseda, said, “What is happening right now in Moscow is a game changer in this war.” Russians, he added, “will realize this is not about watching war on the TV screen, but this is about the war on their own soil.”

Dmitri S. Peskov, the Kremlin spokesman, mocked Europeans for their approach to potential negotiations.

“They believe that they need to talk to Russia from a position of strength,” he told reporters. “Such talks will lead nowhere.”

Mr. Putin has said nothing publicly about Thursday’s bombardment of Moscow. Igor Sechin, the chief executive of the state-owned oil giant Rosneft, acknowledged on Friday that Russia was facing problems with fuel supplies. But he said those issues were related in part to “unscheduled maintenance at refineries,” in what appeared to be a euphemism for the scores of Ukrainian attacks on Russian oil infrastructure in recent months.

The mood in Ukraine is bullish as it brings the war home to Russia. The feeling was summarized by a meme that showed Mr. Zelensky sitting across from Mr. Trump in France. The photograph was edited to fill both of the Ukrainian leader’s hands with playing cards and even cover his suit in them.

The joke was a reference to Mr. Trump’s claims last year that Ukraine had no cards in the war.

Mr. Zelensky used the sit-down with Mr. Trump in France to request permission for blueprints for Patriot air defense systems, the only weapon in the Ukrainian arsenal that can reliably shoot down ballistic missiles.

Such an arrangement, which has not yet been approved, would allow Ukraine to expand its supply of the systems by building them at home rather than waiting for deliveries from partners that buy them from the United States.

The Ukrainian foreign minister, Andrii Sybiha, reposted a photo of Thursday’s attack on social media. “In Moscow, everything is going according to plan,” he wrote. “Not Russia’s plan, though.”

Ukraine continued to fire drones at Moscow on Friday, and the regional governor said that an 8-year-old girl had been killed.

Several Ukrainian civilians were killed in Russian attacks overnight, including a girl, also 8, in the eastern city of Pavlohrad.

Paul Sonne and Valerie Hopkins contributed reporting from Berlin.