He also cited the refusal of China to enter into talks about its expanding nuclear arsenal.
“We may reach a point in the coming years where an increase from current deployed numbers is required,” he said. “We need to be fully prepared to execute if the president makes that decision.
“If that day comes, it will result in a determination that more nuclear weapons are required to deter our adversaries and protect the American people and our allies and partners.”
It comes as Emmanuel Macron said on Friday night that he wanted to “finalise” the creation of a coalition of military instructors for Ukraine in the coming days.
“We will use the days to come to finalise the largest possible coalition to implement Ukraine’s demand,” said Mr Macron at an Elysée press conference with Volodymyr Zelensky, calling it a “legitimate” demand.
Denouncing what he called “the pacifist camp” and a “spirit of defeat” over Ukraine, he said: “France is on the side of peace but peace isn’t capitulation to the aggressor.”
“It is Russia that is attacking civilian infrastructure and civilians, which is a war crime,” he said, adding that Russia should “not betray its own history when in 1944 it resisted” Nazism.
Mr Zelensky also met with Mr Biden and in Paris where the US president apologised for the congressional logjam that delayed military support to Kyiv for six months.
Announcing a new $225 million (£177 million) package of support, including air defence missiles and protection for the Ukrainian electric grid, the US president said: “I apologise for the weeks of not knowing what’s going to pass in terms of funding because we had trouble getting the Bill that we had to pass that had the money in it.
“Some of our very conservative members were holding it up. But we got it done finally. We’re still in – completely, thoroughly.”
The six-month blockade was resolved in April with a new funding package designed to see Ukraine’s defences through to the presidential election in November.
Speaking later from Pointe du Hoc, a former German fortification above Omaha beach, Mr Biden channelled the spirit of D-Day troops and warned about present dangers to democracy and freedom.
“As we gather here today, it’s not just to honour those who showed such remarkable bravery that day, June 6, 1944,” he said.
“It’s to listen to the echo of their voices. They’re not asking us to scale these cliffs. They’re asking us to stay true to what America stands for.”
He made coded reference to Donald Trump, his election rival, but focused his attention on Russia’s war in Ukraine.
“The most natural instinct is to walk away, to be selfish, to force our will upon others,” he said.
Jake Sullivan, Mr Biden’s national security adviser, told reporters the president intended to draw a “through line” between the Second World War, the Cold War, and the present conflict in Europe.