Delays in weapons deliveries from Western allies to Ukraine are opening a door for Russian battlefield advances, Ukrainian President Volodymyr Zelensky says, making the fight “very difficult” along parts of the front line where the Kremlin’s forces captured a strategic city last weekend ahead of the war’s two-year anniversary.

Zelensky and other officials have often expressed frustration at the slowness of promised aid deliveries, especially since signs of war fatigue have emerged. European countries are struggling to find enough stocks to send to Kyiv, and US help worth $60 billion is stalled over political differences. That appears to be playing into the hands of Russian President Vladimir Putin.