UK Prime Minister Rishi Sunak has asked for an assessment of the progress of the war in Ukraine, BBC News reported.

Senior figures fear the PM may be taking an overly cautious approach as the war enters a key phase.

Downing Street insists that Sunak is strongly supportive of Ukraine.

In a tweet, Sunak said the UK was with Ukraine "all the way" during a visit to the country last month, his first overseas trip as prime minister.

But the request for the aforesaid assessment has raised alarm bells in some corners of Whitehall—i.e., the UK government—as military chiefs say weapons supplies to Ukraine may prove decisive in the winter months ahead.

The Whitehall source said: "Wars aren't won [by dashboards]. Wars are won on instinct. At the start of this it was Boris (Johnson) sitting down and saying: 'Let's just go for this.' So Rishi needs to channel his inner Boris on foreign policy though not of course on anything else."

The source said the audit, known as a data-driven assessment, is designed to assess the progress of the war and the significance of the UK's military contributions to Ukraine.

BBC Newsnight has been told that Volodymyr Zelenskyy, the president of Ukraine, is aware of the debate within the UK and is encouraging Sunak to maintain strong military support for his country.

The proposed assessment of the war comes at a crucial point in the conflict. Key figures in Whitehall believe that Ukraine and Russia have fought themselves to a standstill.

The only way, they say, for one side to pull ahead is by substantially increasing their supply of weaponry.

Whitehall sources say that Admiral Sir Tony Radakin, the chief of the defense staff, delivered that message in diplomatic terms in a lecture this week.

Sir Tony made clear the Russian military "cupboard is bare," and he appeared to issue a rallying cry for continued support for Ukraine.

The US Congress gave the Pentagon approval in principle earlier this month to buy substantial weaponry for Ukraine. But the Economist reported that this may not arrive in time for a spring offensive next year.

Some in Whitehall see this approach as a sign of the innate caution on Ukraine by US President Joe Biden who is understood to be concerned about provoking a wider global conflict. There are some fears in Whitehall that Sunak may end up encouraging Biden's caution.