Mr Biden also said he would rally democracies in an ideological and economic struggle against China and face down provocations from Russian Federation as he left Washington on his first overseas trip as president.
During the preplanned call, Sullivan said, "they had an opportunity to talk at some length about all of the issues in the U.S. -Ukraine relationship, and President Biden was able to tell President Zelensky that he will stand up firmly for Ukraine's sovereignty, territorial integrity and its aspirations as we go forward". He will try to improve relations after they soured under former President Donald Trump.
Biden, 78, heads from the White House first to Britain ahead of a G7 summit in a Cornish seaside resort from Friday to Sunday.
Russian President Vladimir Putin takes part in a ceremony to unveil a monument to Russian Emperor Alexander III of Russia, in Gatchina, about 45 kilometers south of St. Petersburg, Russia, Saturday, June 5, 2021.
Russian President Vladimir Putin on Monday signed a bill to withdraw from an worldwide treaty allowing surveillance flights over military facilities, following the USA exit from the pact.
The EU and Russian Federation disagree on a wide range of issues including human rights, Russia's intervention in Ukraine and Moscow's treatment of jailed Kremlin critic Alexei Navalny, and Michel said that relations between them had reached a low point. They will discuss shared strategic challenges, including climate change and the withdrawal of troops from Afghanistan. The world leaders are expected to endorse the plan, though it's already facing opposition from Republicans in the United States.
The week-plus journey is a big moment for Biden, who traveled the world for decades as vice president and as chair of the Senate Foreign Relations Committee and will now step off Air Force One onto global soil as commander in chief.
His first stop late Wednesday will be an address to US troops stationed in Britain, and the next day he sits down with British Prime Minster Boris Johnson.
As he left for Europe, Biden told reporters he planned on announcing a vaccine plan for the world.
"The trip, at its core, will advance the fundamental thrust of Joe Biden's foreign policy to rally the world's democracies to tackle the greatest challenges of our time", White House National Security Adviser Jake Sullivan told reporters at a briefing on Monday.
But Press Secretary Jen Psaki said that with decades in the Senate and eight years as vice president under Barack Obama, Biden has done his homework.
The meetings are a build-up to his face-to-face meeting with Putin in Geneva on Wednesday.
Sullivan said Biden is intentionally having the sitdown after consulting with and building support among democratic allies during the G7 and North Atlantic Treaty Organisation meetings, in order to come into the meeting with "the wind at his back". "There is simply a lot we have to work through".
When asked if he would reach an agreement with Putin on cyberattacks, Biden did not make any commitments.