Ukrainian President Volodymyr Zelensky will on Friday address the French parliament and US President Joe Biden give a keynote speech on democracy after world leaders marked 80 years since the D-Day landings in World War II.
Biden, Britain's King Charles III, Canadian Prime Minister Justin Trudeau and French President Emmanuel Macron paid tribute Thursday to the tens of thousands of Allied troops who stormed the beaches of Normandy in northern France on June 6, 1944.
An additional guest was Zelensky, in a stark reminder of the war being waged for over two years in Europe following Russia's invasion of Ukraine in February 2022.
He was due to address the National Assembly, France's lower house of parliament, from around 0745 GMT before talks with Macron later Thursday.
Late Friday, Biden will return to Normandy to give a speech at the Pointe du Hoc, a clifftop promontory where German bunkers were attacked by US troops in a daring assault during the landings, on defending freedom and democracy.
The speech is likely to be seen as a warning against his rival and ex-president Donald Trump in the US presidential election later this year.
Macron will also give a keynote speech in Bayeux, the first French town to be liberated from German occupation after D-Day.
Biden vowed Thursday never to abandon international alliances or Ukraine in its fight against Russia, a pointed swipe at Trump, who has publicly questioned the importance of organisations such as NATO.
"We're living in a time when democracy is more at risk across the world than at any point since the end of World War II," Biden said.
"Isolationism was not the answer 80 years ago and is not the answer today," he said.
"Real alliances make us stronger -- a lesson that I pray we Americans never forget."
Biden also vowed that under his leadership, the United States "will not walk away" from Ukraine "because if we do, Ukraine will be subjugated and it will not end there".
"Ukraine's neighbours will be threatened, all of Europe will be threatened," he said, describing Russian President Vladimir Putin as a "tyrant bent on domination".
To surrender to bullies or "bow down to dictators" is "simply unthinkable", he said.
His message that D-Day provided lessons for the present was echoed by Macron, who spoke at a ceremony attended by Zelensky overlooking Omaha Beach, where US troops came ashore in 1944.
"Thank you to the Ukrainian people for their bravery," Macron said as guests rose in a standing ovation to acknowledge Zelensky, and French jets roared above in a fly-past.
"We are here and we will not weaken," he said.
Kyiv has been pushing Europe to increase its military support, with Russia gaining the upper hand on the battlefield in recent months and concerns growing over what a Trump presidency could mean for the conflict.
Speaking to French television, Macron said France would transfer Mirage-2000 fighter jets to Ukraine and train Ukrainian pilots as part of a new military cooperation with Kyiv.
Macron said he would propose to Zelensky during talks at the Elysee Palace that the pilots be trained starting this summer.
He added that Western allies would consider a request from Ukraine to send military instructors to train its forces on its soil to meet the growing challenge of building up troop numbers.
