The G7 has agreed to use frozen Russian assets to raise $50bn (£39bn) for Ukraine to help it fight invading Russian forces.
US President Joe Biden said it was another reminder to Russia "that we're not backing down", but in Moscow President Vladimir Putin said the move was "theft" which would "not go unpunished".
Also at the G7 summit in Italy, Ukrainian President Volodymyr Zelensky and Mr Biden signed a 10-year bilateral security deal between Ukraine and the US, hailed by Kyiv as "historic".