Britain’s top diplomat rebuked Donald Trump Monday after the U.S. presidential hopeful issued a threat to the NATO military alliance.

David Cameron, Britain’s foreign secretary, stressed he was a “very strong supporter of NATO,” and said Trump’s contention Russia could “do whatever the hell they want” to NATO members who don’t contribute enough is “not a sensible approach.”

Trump sparked outrage across Europe after he told a rally in Conway, South Carolina, that he would “encourage” Russia to invade NATO allies who are “delinquent,” saying “you gotta pay. You gotta pay your bills.”

But speaking to reporters in Scotland, Cameron said the military alliance is “what helps to keep us safe — and that is so essential in this world where we have seen Putin’s terrible, illegal invasion of Ukraine.”

“Of course we want all countries, like us, to spend 2 percent (of GDP on defense), but I think what was said was not a sensible approach,” Cameron added.

No. 10 Downing St. responded to Trump’s remarks Monday by saying the U.K. remains “fully committed to standing with our allies to combat Russian aggression.”

The U.K.’s rejection of Trump’s comments comes amid a wider pushback across Europe.

On Monday Polish Prime Minister Donald Tusk argued that the alliance should never waiver in its ideal of “All for one, and one for all!”