US president says Washington is still ‘completely, thoroughly’ standing with Kyiv to fend off the Russian invasion.

United States President Joe Biden has apologised to his Ukrainian counterpart Volodymyr Zelenskyy for previous delays in Washington’s aid to Kyiv, stressing that the US is “not going to walk away” from supporting Ukraine.

The two leaders met on Friday in Paris on the sidelines of D-Day anniversary celebrations, where the US president announced a $225m aid package to help rebuild Ukraine’s electric grid.

Biden emphasised that the US will continue to stand with Ukraine against the Russian invasion. “We’re still in – completely, thoroughly,” he said.

Washington has provided tens of billions of dollars to Kyiv to help fend off the Russian offensive that began in February 2022. But earlier this year, funds available for the Biden administration to help Ukraine began to dwindle during an impasse in Congress to authorise new aid.

Some right-wing lawmakers have been sceptical of US support for Ukraine. Further complicating matters, legislators tried to link Ukraine aid to other issues, including assistance to Israel and domestic priorities.

After months of negotiations between the White House and congressional leaders, lawmakers passed a $61bn Ukraine funding bill in April that Biden signed into law. The legislation also provided $14bn in military aid to Israel.

“I apologise for the weeks of not knowing what’s going on in terms of funding,” Biden told Zelenskyy, blaming “very conservative” members of Congress for holding up the funding bill.

Russia launched its all-out invasion of Ukraine after a months-long standoff that saw Moscow amass troops near the Ukrainian border as Russian President Vladimir Putin demanded an end to NATO expansion into former Soviet republics.

Ukrainian forces stopped Russia’s advance on Kyiv early in the war and pushed back the Kremlin’s troops in some areas. But the conflict slowly turned into a protracted war with most of the fighting taking place in eastern Ukraine.

A Ukrainian counteroffensive last year failed to make significant territorial gains. In recent weeks, Russia has renewed attacks on Kharkiv, a city in northeastern Ukraine that is 30km (20 miles) from the Russian border.

On Friday, Biden lauded what he called Ukraine’s “impressive” war efforts against Russia.

“You haven’t bowed down. You haven’t yielded at all. You continue to fight in a way that is remarkable,” he told Zelenskyy.

Last month, Washington said it gave Kyiv the green light to use US-provided weapons to attack targets inside Russia to help protect Kharkiv.

Zelenskyy on Friday suggested the move is making a difference in the conflict.

“Your decisions have had [a] positive influence. I don’t want to share everything, all the details, with the press, sorry,” Zelenskyy told Biden. “But I think there are some details on the battlefield you need to hear from us. We’re thankful for this.”