‘Russia won’t Prevail’, says Joe Biden as he hosts Zelenskyy in White House

Ukrainian president Volodymyr Zelenskyy met with US president Joe Biden at the White House to present his wartime "victory plan," after Biden announced an $8 billion surge in military aid for Kyiv's fight against Russia.

"Russia will not prevail. Ukraine will prevail, and we'll continue to stand by you every step of the way," Biden said on Thursday as he hosted Zelenskyy in the Oval Office, after thanking him for presenting the so-called victory plan.

Dressed in his trademark military-style outfit, Zelenskyy replied that "we deeply appreciate that Ukraine and America have stood side by side".

But Zelenskyy's visit was clouded by a blazing row with Republican presidential candidate Donald Trump that underscored how November's US election could upend the support that Kyiv receives from its biggest backer.

Zelenskyy is looking to shore up support for his war effort at the same time as Biden tries to lock in aid for Ukraine, ahead of the white-knuckle vote pitting Biden's Vice-President Kamala Harris against firebrand Trump.

The Democrat pledged nearly $8 billion in military aid in his announcement on Thursday, including $5.5 billion to be authorised before it expires at the end of the US fiscal year on Monday.

Biden said in a statement that the "surge in security assistance for Ukraine" would "help Ukraine win this war".

Biden also announced Washington would provide Ukraine with the Joint Standoff Weapon (JSOW) long-range munition and called a summit of allies in Germany in October.

The White House however played down Ukraine's hopes that Zelenskyy's visit would achieve his long-held goal of getting permission to fire long-range Western-made missiles into Russian territory.

"I'm not expecting there to be any new announcements on this particular action or a decision coming out of this meeting," Press Secretary Karine Jean-Pierre told reporters.

Harris was due to meet Zelenskyy separately at the White House on Thursday.

Zelenskyy also visited the US Congress -- where his government said he had also presented his victory plan -- and gave a defiant address at the UN General Assembly on Wednesday.

But Zelenskyy's visit has prompted fresh nuclear saber rattling from Moscow, which has repeatedly warned the West against giving Ukraine long-range arms.

Russian President Vladimir Putin on Wednesday announced plans to broaden Moscow's rules on the use of its atomic weaponry in the event of a "massive" air attack.

US Secretary of State Antony Blinken called the nuclear threat "totally irresponsible" while EU foreign policy spokesman Peter Stano said Putin was making a "gamble with his nuclear arsenal".

Kyiv faces an increasingly difficult battlefield situation two and a half years into Russia's invasion, with Russian forces continuing to push into eastern Ukraine.

But the US presidential election means Washington's support now hangs on the balance -- and with Zelenskyy apparently at odds with Trump and the Republicans.

Trump had also been due to meet Zelenskyy during his US visit, but their talks now appear to be on ice.

Trump accused Zelenskyy on the eve of the visit of refusing to strike a deal with Moscow and once again questioned why the United States was giving billions of dollars to Kyiv.

At an election rally on Wednesday, the Republican called the Ukrainian President "probably the greatest salesman on Earth".

Republicans were livid after Zelenskyy visited an arms factory in Biden's hometown in the battleground state of Pennsylvania earlier this week, with House Speaker Mike Johnson calling for the Ukrainian ambassador to be sacked.

Zelenskyy also sparked fury in Republican ranks when he told The New Yorker magazine this week that Trump and his running mate J.D. Vance did not understand the war's complexity.

Trump has echoed many of Putin's talking points about previous US policy being to blame for the Russian invasion, and has been critical of Zelenskyy for years.

The US has provided around $175 billion in both military and economic assistance to Ukraine during the war, despite frequent opposition from Republicans.