Britain's King Charles III welcomed Canadian Prime Minister Justin Trudeau on Monday as the monarch faces criticism in Canada over being silent about U.S. President Donald Trump’s repeated suggestion that the U.S. annex its northern neighbor.

While royal officials did not provide details about the private talks at the monarch’s royal residence Sandringham, the king and Trudeau were expected to discuss Trump’s comments that Canada should become the 51st state.

Charles is the head of state in Canada, a member of the Commonwealth group of many former British colonies and territories. Trudeau said Sunday, “nothing seems more important to Canadians right now than standing up for our sovereignty and our independence as a nation.”

Britain’s monarchs must remain politically neutral, but the Canada issue shows how delicate that balancing act can be.

“The Government of Canada should ask the Head of State to underscore Canadian sovereignty,” former Alberta Premier Jason Kenney posted on X.

Trudeau flew to London to join an emergency defense summit on Ukraine over the weekend, where British Prime Minister Keir Starmer outlined plans to end the war in Ukraine and rallied European counterparts to throw their weight behind the country as U.S. backing of Ukraine appeared in jeopardy.

The king's meeting with the Canadian leader came after Charles met Sunday with Ukrainian President Volodymyr Zelenskyy to show solidarity with Ukraine after Trump lashed out at Zelenskyy in a heated exchange in the Oval Office.

Starmer told lawmakers Monday he held talks with Trudeau over the weekend and was "able to assure him of our strong support for Canada.”

Meanwhile, Charles has invited Trump to come for a state visit. Starmer delivered that invitation to Trump in Washington last week, noting it was an “unprecedented” honor since Trump already had been given the royal treatment by Queen Elizabeth II during his first term.

Starmer insisted to lawmakers Monday that the U.S. and Britain have “the closest of relationships,” and that it would be "a huge mistake at a time like this to suggest that any weakening of that link is the way forward for security and defense in Europe.”