US President Joe Biden has reassured his Ukrainian counterpart that $60bn in military aid is en route. The measure still requires final congressional approval, but President Biden conveyed his confidence to Volodymyr Zelensky that it would be sanctioned. President Zelensky had previously made an urgent plea for additional weapons to prevent a "catastrophic" situation in Europe.

The US has attributed Ukraine's retreat from the battle at Avdiivka to a lack of Congressional support. Russia's recent seizure of Avdiivka, a crucial access point to the Russian-held Donetsk regional capital in the east, marks their first significant advance since the capture of nearby Bakhmut in May. 

"Ukraine's military was forced to withdraw from Avdiivka after Ukrainian soldiers had to ration ammunition due to dwindling supplies as a result of congressional inaction," - a White House statement read.

Earlier this week, the US Senate endorsed a $95bn foreign aid package, which encompasses $60bn for Ukraine, following months of political disputes. However, the package still faces an uphill battle in the House of Representatives, where Republican members are divided on the issue.

Following his discussion with President Zelensky on Saturday, President Biden told reporters, "Look, the Ukrainian people have fought so bravely and heroically, they've put so much on the line, and the notion that now, when they're running out of ammunition, we'd walk away - I find it absurd. I find it unethical, I find it just contrary to everything we are as a country. So I'm going to fight until we get them the ammunition they need and the capacity they need to defend themselves".