European Union leaders unexpectedly agreed on Thursday to open accession negotiations with Ukraine, a momentous moment and a stunning reversal for a country at war that had struggled to find the backing for its membership aspirations and long faced obstinate opposition from Hungarian Prime Minister Viktor Orban.

European Council President Charles Michel, who was chairing a Brussels summit of the EU's 27 leaders where the decision was made, called it "a clear signal of hope for their people and our continent."

EU diplomats and officials said the unexpected green light for talks took place as Orban – who had for weeks said he would block such a deal – agreed to leave the room, knowing the other leaders would go ahead and vote.

Orban confirmed that he had abstained from the vote on what he called a "bad decision." It was unclear at this stage what exactly he could be getting in return.

Although the process between opening negotiations and Ukraine finally becoming a member could take many years, Ukrainian President Volodymyr Zelenskyy welcomed the agreement as "a victory for Ukraine. A victory for all of Europe."

"I congratulate every Ukrainian on this day ... History is made by those who don't get tired of fighting for freedom," Zelenskyy said.

Orban said his opposition remained steadfast, but, with a unanimous decision required, he decided to let his right to oppose lapse because the 26 others were arguing so strongly in favor. An abstention from him was not enough to stop the decision from being adopted.

Such an unusual way to approve a decision – especially such a major one – is unheard of in Brussels, even for a place where diplomats have long been very creative about how to strike deals.

Several diplomats said German Chancellor Olaf Scholz came up with the suggestion that Orban leave the room so the decision could be approved.

European Commission chief Ursula von der Leyen said it was "a strategic decision and a day that will remain engraved in the history of our union."

Orban had very different words to describe the decision.

"Hungary's perspective is clear: Ukraine is not ready for us to begin negotiations on its EU membership. It's a completely illogical, irrational and improper decision" Hungary's prime minister said.

"But 26 member states were adamant that this decision must be made so Hungary decided that if 26 decide so, they should go on their own path and Hungary does not wish to participate in this bad decision," he noted.

Others lauded Orban's gesture; they were preparing for a summit that some feared might spill over into an extra day Saturday.

"Certainly quicker than any of us expected," Irish Prime Minister Leo Varadkar said.

"In fairness to Prime Minister Orban, he made his case, made it very strongly. He disagrees with this decision and he's not changing his opinion in that sense, but essentially decided not to use the veto power," Varadkar said.

"I have to say, I respect the fact that he didn't do that, because it would have put us in a very difficult position as a European Union," the Irish leader added.

Belgium's Prime Minister Alexander De Croo had a slightly different take, saying he thought Orban "didn't use his veto because he realized that it would be indefensible."

Left on the summit agenda now is a promise to give Ukraine the money and wherewithal to stave off Russia's invasion, another agenda item held up by Orban.

The Hungarian leader came into the summit, the last of the year, vowing to both block the plans by his 26 fellow leaders to officially declare that membership negotiations with Ukraine can start, and more pressingly, deny Kyiv 50 billion euros ($54 billion) in financial aid that the country desperately needs to stay afloat.

"The European Union is about to make a terrible mistake and they must be stopped – even if 26 of them want to do it, and we are the only ones against it," Orban said in comments released by his office Thursday. "This is a mistake, we are destroying the European Union."

Other EU leaders had warned that not agreeing to start negotiations would have been seen as a victory for Russian President Vladimir Putin.

Belgium's De Croo said the decision was as much a message to Kyiv as it was to Moscow.

"It is a very clear message to Moscow. Us Europeans, we don't let go of Ukraine," De Croo said.

A beaming Michel came down in the summit media room unscheduled and said "This is a historic moment, and it shows the credibility of the European Union. The strength of the European Union. The decision is made."

He said the negotiations would open before a report will be made to the leaders in March.

"It was important that no member state would oppose this decision," said Michel, adding he was confident a consensus could be found on the financial aid.

The surprise came at a dire time for Zelenskyy, straight off a trip to Washington where his pleas for more aid from the U.S. Congress fell on deaf ears.

The urgency to find a solution is matched only by the potential blow to the EU's credibility, the Ukrainian president said in a video address to the leaders assembled in Brussels.

"Nobody wants Europe to be seen as untrustworthy. Or as unable to take decisions it prepared itself," he said.

Referring to Putin, he added, "Don't give him this first – and only – victory of the year. Europe must win, agreements must be honored."

"Whatever it takes" had been the relentless mantra of the EU in pledging its support, leaders dressed up in the yellow and sky-blue colors of Ukraine, and countless speeches ending with the rallying cry "Slava Ukraini!" – "Glory to Ukraine!"

And again, against the odds, the EU prevailed.

The EU, a group of 27 nations that still cherish their independence on strategic and foreign affairs issues, works by unanimity on most issues relating to Ukraine. Orban was seen by many as Putin's foot in the summit door to demolish the bloc's support for Zelenskyy and his country.

Orban has complained of corruption in Ukraine and demanded a "strategic discussion" on the country's future in Europe as the war with Russia bogs down and concerns mount about what kind of administration might emerge in Washington after the U.S. elections in a year.

The Hungarian leader has been at odds with his fellow EU leaders for years, ranging from fights over COVID-19 recovery money to his declining respect for the Western democratic principles that are the essence of the EU. Yet, as the longest-serving EU leader, he knows how to play the summit room like few others and has been able to extract financial concessions time and again to shore up his struggling economy.

In intense diplomacy, Scholz and French President Emmanuel Macron met with Orban before the summit, alongside von der Leyen and Michel.

The EU relented on Wednesday and granted Hungary access to over 10 billion euros ($11 billion) in funds that had been frozen by the European Commission out of concern that democratic backsliding by Orban could put the bloc's principles at risk.

The commission said it did so after Budapest had made the necessary concessions on the rule of law principle and denied it was a bargaining chip.

Michel said the European Council had also decided on Thursday to open formal accession negotiations with Moldova.

Moldova's President Maia Sandu welcomed the agreement, saying his country was "committed to the hard work needed to become an EU member."

"Moldova turns a new page today with the EU's go-ahead for accession talks," Sandu wrote on social media platform X, formerly known as Twitter. "Moldova is ready to rise to the challenge."

He went on to say the summit granted EU candidate status to Georgia and would also advance an EU bid by another hopeful – Bosnia-Herzegovina – once it reaches "the necessary degree of compliance" with criteria.