US President Joe Biden will use the remaining four months of his term “to put Ukraine in the best possible position to prevail”, a close advisor said Saturday.

Speaking remotely to a forum in Kyiv, US National Security Advisor Jake Sullivan also said Biden will meet Ukrainian President Volodymyr Zelensky in late September at the UN General Assembly in New York to discuss aid to Ukraine.

“President Zelensky has said that ultimately this war has to end through negotiations, and we need them to be strong in those negotiations,” Sullivan said, adding Ukraine would decide when to enter talks with Russia.

Biden will be replaced next January either by his Vice President Kamala Harris, who has indicated she will continue his policies of backing Ukraine, or by former president Donald Trump, who would not say at a debate earlier this week whether he wanted Kyiv to win the war.