A day after Congress forged ahead with a mammoth US financial commitment to Ukraine, the EU’s continued determination to confront President Vladimir V. Putin of Russia was being tested on Wednesday as EU ambassadors again failed to reach an agreement to ban Russian oil.

Talks in Brussels broke off for the day as Hungary, which has resisted adopting an embargo on Russian oil, emerged as the most consequential spoiler to Europe’s continued efforts to present a united front against Moscow as the fighting in Ukraine drags on.

Even as the EU has never been more unified or determined than now, the Hungary dispute is a window into how fractures could happen that help Putin.

Although EU leaders have already approved five sanctions packages against Russia, their struggles to finalise this latest, toughest measure — one that would heavily punish Russia but also inflict pain on the bloc’s own economies — underscored what US intelligence officials have warned that Putin is counting on: a weakening of western resolve as he girds Russia for a protracted conflict.

“Putin most likely also judges that Russia has a greater ability and willingness to endure challenges than his adversaries,” the US director of national intelligence, Avril D. Haines, told lawmakers on Tuesday. “And he is probably counting on US and EU resolve to weaken as food shortages, inflation and energy prices get worse.”

While Russia appeared to be nearing one of its stated aims, control of the Donbas region in eastern Ukraine, Haines said that would neither satisfy Putin nor bring his war to an end.

Battlefield gains

Ukrainian forces reported battlefield gains on Wednesday in a counterattack that could signal a shift in the momentum of the war, while Kyiv shut gas flows on a route through Russian-held territory, raising the spectre of an energy crisis in Europe.

Following days of advances north and east of the second largest city Kharkiv, Ukrainian forces were just kilometres from the Russian border on Wednesday, one Ukrainian military source said on condition on anonymity. Before the advance, Russian forces had been on the outskirts of Kharkiv.

New York Times News Service and Reuters