US President Joe Biden has apologised to his counterpart Volodymyr Zelensky for delays in military aid to Ukraine and has pledged $225m (£191m) in support.
The pair met for talks in Paris, a day after they both attended the 80th anniversary commemorations of the D-Day landings in Normandy, France.
The US Department of Defense said the new aid package would include ammunition and anti-aircraft missiles.
Russia launched a full-scale invasion of Ukraine in February 2022.
Mr Biden said previous delays in aid had been caused by some Republicans in Congress, but reiterated US support for Ukraine.
"The United States will stand with you," Mr Biden told Mr Zelensky. "You haven't bowed down. You haven't yielded at all. You continue to fight in a way that is just remarkable, just remarkable."
In response, Mr Zelensky stressed the importance of his country's relationship with the US, saying it was crucial in the fight against Russia: "We count on your continuing support in staying with us shoulder to shoulder."
After meeting Mr Zelensky, Mr Biden made a passionate speech at Pointe Du Hoc, a site in Normandy where US army rangers scaled a cliff to storm a Nazi stronghold on D-Day.
The US president spoke about the sacrifice of those who lost their lives on 6 June 1944, saying: "Does anyone doubt that they would want America to stand up against Putin's aggression here in Europe today?"
"They're asking us to do our job: to protect freedom in our time, to defend democracy, to stand up to aggression abroad and at home," he added.