Earlier, Ukraine's President Volodymyr Zelenskyy urged the leaders to provide more military aid so the country can fight Russia's invasion. He spoke with the leaders over video links.
The unusual series of meetings were organized by NATO, the Group of Seven industrialized nations and the European Union.
Western leaders continue the search for ways to increase pressure on Russian President Vladimir Putin, but avoid anything that could expand military actions.
Zelenskky spoke to a NATO gathering by video from Kyiv. He called for "military assistance without limitations" as Russia is "without limits using its entire arsenal." He asked for anti-air and anti-ship weapons.
He urged NATO to provide Ukraine with one percent of all its tanks and planes.
"We can't just buy those," Zelenskyy said. "When we will have all this, it will give us, just like you, 100 percent security."
Biden, who is attending all three meetings, said more aid was on its way.
"We are committed to identifying additional equipment, including air defense systems, to help Ukraine," Biden said in a written statement after the NATO meeting.
Billions of dollars worth of military equipment have already been provided. An American official said Western nations were discussing the possibility of providing anti-ship weapons. There are concerns that Russia will launch attacks against Ukraine from the Black Sea.
The Biden administration announced that the U.S. will welcome 100,000 Ukrainian refugees and provide an additional $1 billion in food, medicine, water and other supplies.
It also said it will increase sanctions against Russia to include lawmakers and owners of weapon manufacturing companies.
The leaders also discussed Russia's most dangerous weaponry, including biological, chemical and nuclear arms.
Biden has said that possibility is a "real threat." Earlier this week, Putin spokesman Dmitry Peskov told CNN that Russia could consider using its nuclear weapons if it felt there was "an existential threat for our country."
One European diplomat said Western leaders would continue having quiet discussions on what to do if Russia uses what would be the world's first use of a tactical nuclear weapon.
The Russian invasion has caused European nations to reconsider their military spending. Stoltenberg opened the NATO meeting by saying NATO must accept "a new security reality in Europe."
"We are united in condemning the Kremlin's unprovoked aggression," Stoltenberg said.
There is a worry that unity will be tested as the cost of the war begins to affect the international economy.
The increase of forces along NATO's edge will also put financial pressure on its member countries.
I'm Susan Shand.