Donald Trump’s treatment of Ukraine President Volodymyr Zelensky was “wrong”, former prime minister Rishi Sunak has said.

The US president’s criticism of Zelensky, culminating in an explosive Oval Office meeting last week that collapsed talks on American support for Ukraine, was “very hard to watch,” Sunak said.

And Britain must boost defence spending to adjust to the “new world” where it must defend itself with less help from the US, Sunak added.

The former PM was speaking to the BBC’s Political Thinking with Nick Robinson before the US announced it was pausing military aid to Ukraine, in his first major interview since his 2024 election defeat.

Since coming to office, Trump has repeatedly criticised Zelensky.

Trump has called him a “dictator without elections”, claimed he was doing a “terrible job” and falsely suggested he was the one who started the war with Russia.

Trump – who has long called for European members of the Nato military alliance to spend more on defence – is also attempting to cut a rapid deal to bring the Ukraine war to an end after speaking to Russian President Vladimir Putin.

Last week, a White House meeting on a mineral deal – seen as key to continuing US support of Ukraine – erupted into argument. Trump and his Vice President, JD Vance, accused Zelensky of not being grateful enough.

The angry exchange meant the deal, that would give the US access to Ukraine’s deposits of rare earth minerals, was left unsigned.

Sunak said it was “very hard to watch”.

“For him to have been treated that way was wrong,” he added.

Speaking to the BBC, Sunak emphasised his close relationship with Zelensky – having visited Kyiv during his time as prime minister.

Sunak stressed he agreed with Trump that Europe needed to take more responsibility for its own defence and not rely solely on the US.

“We can’t expect America to bear any burden for our security if we are not prepared to make those sacrifices ourselves,” he said.

“What has happened over the last few weeks has been clarifying, and we have just had to be open and honest about that now.”

Pressed on whether the UK needs to prepare for the US to pull out of military support for Europe, Sunak said: “Of course we need to prepare to protect ourselves.

“That is the first job of any British prime minister.

“We are living in a new world that all of us are going to have to adjust to – and that was the case even before the US election.”

As prime minster, Sunak committed the government to increase defence spending to 2.5% by 2030.

The plans were accelerated by Labour, who last week set out plans to hit the target by 2027 – funded through a cut to Overseas Development Aid.

Trump announced he was pausing US military aid to Ukraine on Monday night.

Weapons and military equipment not already in Ukraine will be stopped from reaching its armed forces. The fate of $3.9bn (£3bn) in remaining funding committed by the Biden administration remains unclear.

The freeze emerged after Trump had launched a fresh attack on Zelensky, claiming that he “doesn’t want there to be peace as long as he has America’s backing”, adding that the US “will not put up with it for much longer”.

Then in a statement on Tuesday, Zelensky said he was willing to work under Trump’s “strong” leadership, saying: “Ukraine is ready to come to the negotiating table as soon as possible to bring lasting peace closer.”

A summit of mostly European leaders in London on Sunday agreed a four-point plan to guarantee Ukraine’s defence in the event of a peace deal with Russia.

The summit – hosted by Prime Minister Sir Keir Starmer – was intended as a show of support for Ukraine and an attempt to reduce differences between Western countries over Ukraine.

The UK and France said they were working on a European-led solution to the conflict.

Political Thinking: The Rishi Sunak Lessons From Downing Street One will be available on BBC Sounds from Wednesday morning.