President Joe Biden on Thursday announced another $8 billion in security aid for Ukraine, just a day after Russian President Vladimir Putin hinted at a potential change in Moscow’s nuclear doctrine.

In a statement to the Russian Security Council on Wednesday, Putin suggested that any attack by a non-nuclear nation backed by a nuclear-armed nation could be considered a “joint attack,” potentially impacting the war in Ukraine.

The comments came ahead of a planned meeting between Ukrainian President Volodymyr Zelenskyy and President Biden on Thursday, where Zelenskyy is expected to discuss a “victory plan” and likely reiterate his call for long-range strike capabilities.

Ukraine, lacking its own nuclear arsenal, has heavily relied on U.S. military support in its fight against Russia.

Neither the U.S. nor Russia currently has a “no first use policy” regarding nuclear weapons. Putin’s statement aimed to clarify the circumstances under which Moscow might consider using its nuclear arsenal.

“The conditions for Russia’s transition to the use of nuclear weapons are also clearly fixed,” Putin said, according to a Reuters translation of his comments.

Putin stated that Russia could respond with nuclear weapons to conventional attacks, including the use of missiles, drones, and aircraft, posing a “critical threat to our sovereignty.”

Despite the Kremlin’s efforts to downplay the risk of nuclear conflict amidst the Ukraine war, Biden reaffirmed his commitment to Kyiv on Thursday, pledging to help Ukraine “win this war.”

While Biden has maintained a firm stance against using U.S. missiles to strike deep inside Russia, Washington has approved the first shipment of a medium-range precision-guided glide bomb known as the Joint Standoff Weapon, capable of reaching targets up to 81 miles away, Reuters reported.

The missile would allow Ukraine to strike Russian targets from a safer distance, a capability Ukrainian officials have deemed crucial to counter Russian advances on the eastern front.

Biden stated that the $8 billion in aid would be allocated as follows: $5.5 billion from a previously authorized presidential drawdown, set to expire on Monday, and an additional $2.4 billion authorized through the Department of Defense under the Ukraine Security Assistance Initiative.

The president, who also announced plans to send another Patriot air defense battery and extend training for an additional 18 F-16 pilots into next year, commended Ukraine’s achievements with the help of Western partners, including the defense of Kyiv, the recapture of approximately half of the territory initially seized by Russia, and the “safeguard[ing] of its sovereignty and independence.”

“But there is more work to do,” Biden said. “That is why, today, I am announcing a surge in security assistance for Ukraine and a series of additional actions to help Ukraine win this war.”

The push for increased aid to Ukraine comes as the U.S., and by extension Kyiv, face a potential turning point where some fear that further assistance to Ukraine could be significantly reduced.