Joe Biden has said “I don’t think much about Vladimir Putin” as Sir Keir Starmer joined the US President for talks about the conflict in Ukraine.

The pair sat in the Blue Room at the White House on Friday as the Prime Minister spoke of how the UK and US are “strategically aligned” in their attempts to resolve the war.

Sir Keir said the next weeks and months will be “crucial” in Ukraine and said it was “important” the two countries continued to support the eastern European nation in its fight against Russia.

The meeting comes as Ukrainian President Volodymyr Zelensky expressed his frustration at the continued restrictions on the use of Western weaponry against Russian targets.

In a lengthy statement posted on X, Mr Zelensky said after meeting with Foreign Secretary David Lammy and his US counterpart Antony Blinken earlier this week, “there should be no unanswered questions about why Ukraine needs sufficient long-range capabilities”.

At the White House on Friday, Sir Keir told the US President: “Historically, we’ve shown the strength of our relationship.

“We are strategically aligned and we have a common cause on these global issues.”

Mr Lammy and Mr Blinken were pressed on the use of Western weaponry during their visit to Ukraine earlier this week, but said they had to report back to their bosses, the Prime Minister and US President.

Mr Putin said allowing long-range strikes “would mean that Nato countries, the United States, and European countries are at war with Russia … if this is so, then, bearing in mind the change in the very essence of this conflict, we will make appropriate decisions based on the threats that will be created for us”.

Asked what he thought of Mr Putin’s threat of war, Mr Biden said: “I don’t think much about Vladimir Putin.”

Mr Biden thanked Sir Keir for his “leadership” during the Ukraine conflict, adding: “Putin will not prevail in this war”.

He said: “The United States is committed to standing with you to help Ukraine as it defends against Russia’s onslaught of aggression.

“It’s clear that Putin will not prevail in this war. The people of Ukraine will prevail.”

The US President said the two leaders would talk about Ukraine, the need for a hostage and ceasefire deal in the Middle East, and about the Indo-Pacific region.

He told the PM: “I’ve often said there’s no issue of global consequence where the United States and UK can’t work together and haven’t worked yet.”

Before the meeting began, a British reporter was told to “be quiet while I speak” by the US President as Mr Biden was asked about Mr Putin’s threat of war.

Concern about escalation has been one of the reasons why permission has not yet been given to Kyiv for the unrestricted use of Western weapons.

Iran has been hit with sanctions by the UK and US after the two countries formally accused Tehran of supplying ballistic missiles to Russia.

Mr Lammy and Mr Blinken announced further financial support for Ukraine, including a £600 million package from the UK and 717 million dollars (£550 million) from the US to meet immediate humanitarian, energy and stabilisation needs.

The UK package includes a reaffirmation of Rishi Sunak’s pledge of £242 million, as well as 484 million dollars (£371 million) worth of loan guarantees for World Bank lending before the end of the year, while the US package includes 325 million dollars (£250 million) to support Ukraine’s energy needs.

The PM and Mr Biden’s first White House bilateral took place as the Sir Keir attended the Nato summit just days after Labour won the election.