The EU has decided to open membership negotiations with Ukraine, in an unexpected move that will be a critical boost to Volodymyr Zelenskiy and deal a blow to Vladimir Putin. The announcement, made on Thursday after eight hours of tense negotiations in Brussels, came despite the opposition of Hungary, whose prime minister, Viktor Orbán, had for weeks said it would veto any opening of accession talks. In the end, diplomats said, Orbán left the room when the key decision – which had to be unanimous – was made by leaders of the other 26 member states. Even for a city in which the art of deal-making is well honed, it was a highly unusual manoeuvre. Sources said the decision of Orbán not to be in the room was agreed beforehand: “He knew that 26 member states were strongly in favour. Of course it’s legal.” Moments after the decision was announced, Zelenskiy said: “This is a victory for Ukraine. A victory for all of Europe. A victory that motivates, inspires, and strengthens.” On X, the Ukrainian president added: “History is made by those who don’t get tired of fighting for freedom.” There was more good news for Zelenskiy later on Thursday when the US Senate announced it would delay its holiday break – due to start on Friday – in order to vote next week on military aid for Ukraine. Joe Biden has been urging lawmakers to pass a supplemental aid package to provide $50bn in new security to Ukraine, as well as $14bn for Israel, but Republicans have said they will only vote for that aid if it is paired with new controls for the US-Mexico border. The 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”. He added: “This is historic moment that ensures the credibility and the strength of the EU.” After weeks of brinkmanship with Orbán, who had argued that Ukraine was “one of the most corrupt countries in the world”, the decision after less than nine hours of talks behind closed doors came as a surprise. There is no mechanism for a country to abstain on a decision of this magnitude but Hungary suggested it was a decision endorsed by 26 member states rather than 27. Speaking in a video on social media, Orbán said he had not voted as he did not want to take part in what he thought was “a completely senseless, irrational and incorrect decision”. Budapest had decided that the other member states “should go their own way”, he said. “Hungary does not want to share in this bad decision and for this reason Hungary did not participate in the decision today.” It was a far cry from the trenchant position he had appeared to take just hours earlier, when he vowed to block any such move on the enlargement of the EU. Leaders also agreed to open accession negotiations with Moldova and to grant candidate status to Georgia. In a shot in the arm for Bosnia and Herzegovina’s candidacy, negotiations have also been given the green light once the Balkan state meets the “necessary degree of compliances”. The move to open the path for Ukraine comes at a critical time for Zelenskiy, who is struggling to persuade US Republicans to support a $61bn (£47.9bn) military aid package for Ukraine, with objectors insisting on White House concessions over US border security as a condition for a deal. Speaking on Thursday in a marathon end of year press conference, Putin alluded to these and other worries, claiming that western support for Kyiv would soon dry up. “Today Ukraine produces almost nothing,” he said. “Everything is being brought in for free. But that could run out at some point. And it seems that they are gradually running out.” Zelenskiy was so concerned that his country would not get what he needed from the summit that he considered flying to Brussels in a last-minute appeal but in the end it was not needed. Just before the leaders sat down to a lunch of Breton medallion, root vegetables and panettone, the Ukrainian leader made an impassioned plea to leaders not to “betray” his country by dithering on EU membership, which he said would put a “satisfied smile” on Putin’s face. He urged EU leaders to think of all the soldiers who were fighting in the trenches, rather than themselves. “This isn’t about what politicians need. It’s about what people need. All those people in the trenches, shooting down drones and missiles every night,” he said. “And all those working so children can learn even under constant Russian terror, and doctors can save lives even when Russia tries to destroy our energy or communication systems.” Michel said negotiations would now open in March, when a report on the final changes Ukraine must undertake to make the first steps on the path to EU membership is expected to be complete. “This is extremely important; we want to support Ukraine. This is a very powerful political signal, it is a very powerful political decision and today and tonight I think to the people of Ukraine – we are on their side and this decision made by the member states is extremely important for the European Union,” Michel said. The summit will continue into Friday with big decisions on filling the pandemic and energy crisis-sized hole in the EU budget, and discussions on other pressing matters including sanctions on Hamas leaders, Israeli settlers involved in violence and the rise of antisemitism. Late on Thursday, Italy, Germany, the Netherlands and Finland broke off to smooth differences on budget priorities that included a near €10bn allocation for migration issues.