Grant Shapps has risked inflaming tensions with Britain’s most important ally, saying the US only does the right thing after “they have exhausted all other options”.
The defence secretary aimed the barb at his American colleagues after the Senate approved a $61bn military aid package for Ukraine on Tuesday night.
President Joe Biden said he would sign the historic support package on Wednesday.
But, speaking to BBC Radio 4’s Today programme, gaffe-prone Mr Shapps said: “I was relieved to see the US Congress finally pass their package of support for Ukraine.
“It rather reminds me of the old maxim of Winston Churchill, that the United States can always be relied on to do the right thing, once they have exhausted all other options.”
There is dispute over whether the quote, often attributed to Mr Churchill, was actually said by the wartime prime minister.
But Mr Shapps’s invocation of the quote implied the US has been dragging its feet over aid to Ukraine and risks sparking a row with Mr Biden’s administration.
Mr Shapps added: “It is very important that Vladimir Putin understands that the West is going to stand behind Ukraine no matter what it takes.”
The arms and ammunition in the $61bn military aid package should enable Ukraine to slow the Russian army’s bloody advances and block its strikes on troops and civilians. And it will buy Ukraine time — for long-term planning about how to take back the fifth of the country now under Russian control.
The US House of Representatives approved the package on Saturday after months of delays by some Republicans wary of US involvement overseas. It was passed by the Senate on Tuesday, and President Joe Biden said he would sign it Wednesday.
The difference could be felt within days on the front line in eastern and southern Ukraine, where Russia’s much larger army has been slowly taking territory against massively outgunned Ukrainian forces.
The barb by Mr Shapps came a day after Rishi Sunak unveiled plans to hike Britain’s defence spending to 2.5 per cent of GDP by 2030.
At a press conference alongside Nato secretary general Jens Stoltenberg, the prime minister promised an extra £75bn in defence spending over the next six years.
He warned that the world is “the most dangerous it has been since the end of the Cold War”, and pledged to put Britain’s defence industry “on a war footing”.
It was the latest announcement in a recent flurry of activity by Mr Sunak as he seeks to close the polling gap with Labour ahead of a general election this year.
Last Friday he made a speech promising to end Britain’s “sick note culture”, while on Monday he held a rare Downing Street press conference to set out details of how his Rwanda deportation plan will work.
He has come under significant pressure from backbench Conservatives to boost defence spending amid the ongoing war in Ukraine and heightened tensions in the Middle East.
Mr Sunak stressed that the UK is “not on the brink of war”, but warned about the threats facing the world from “an axis of authoritarian states” including Russia, China, Iran and North Korea.
The prime minister is in Berlin today and is set to announce a new partnership on developing artillery systems alongside German chancellor Olaf Scholz.
The two countries will open a “new chapter” in their partnership, Mr Sunak said.
Mr Shapps has a history of making public gaffes, including being caught out by his own travel rules and having to cut short his summer holiday as transport secretary. He also once said on TV that he backed Brexit despite a previous tweet claiming to have voted to remain in the EU.
And after taking up his post in the Ministry of Defence, Mr Shapps was criticised for confusing the RAF with the Royal Navy in his second week in the job.
