US President Joe Biden on Saturday blamed congressional inaction for Russia’s capture of the eastern Ukrainian stronghold of Avdiivka, as partisan wrangling holds up US$60 billion in badly needed military aid.

With Ukrainian forces running low on supplies, Biden called President Volodymyr Zelensky on Saturday “to underscore the United States’ commitment to continue supporting Ukraine”, according to a White House statement summarising the call.

It said the Ukrainian withdrawal from Avdiivka came “after Ukrainian soldiers had to ration ammunition due to dwindling supplies as a result of congressional inaction, resulting in Russia’s first notable gains in months”.

Biden “reaffirmed the strong bipartisan support in the US government and among the American people for Ukraine’s sovereignty and territorial integrity”, and he called on Congress to urgently pass a spending bill including aid for Ukraine.

“The Ukrainians continue to fight bravely, but they are running low on supplies,” National Security Council spokeswoman Adrienne Watson said earlier, adding that Ukraine needed artillery ammunition and other critical equipment.

In a post on Telegram following the phone call, Zelensky said: “I am glad that I can count on the full support of the American president. We also believe in the wise decision of the US Congress.”

The fall of Avdiivka, an industrial city in Ukraine’s eastern Donbas region, was a major symbolic victory for Russian President Vladimir Putin.

Avdiivka, though mostly destroyed by now, had been a symbol of Ukraine’s determined resistance to Russian aggression since 2014.

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The statements of US support came as Vice-President Kamala Harris and Secretary of State Antony Blinken were scrambling to reassure Western allies at the Munich Security Conference that Washington’s support of Kyiv’s war effort against the Russian invasion would continue.

With existing US funding having already dried up, Donald Trump’s allies in the House of Representatives have been stalling crucial Ukraine aid.

Trump, the likely Republican nominee in the November presidential race, opposes helping Kyiv and recently used his sway to kill a US border reform bill that would have also authorised additional aid to Ukraine.

Speaking in Munich earlier Saturday alongside Zelensky, Harris said: “As it relates to our support for Ukraine, we must be unwavering and we cannot play political games.”