Prime Minister Justin Trudeau is headed back to Ottawa, after ending his London visit with an audience with King Charles.

Trudeau was in London for a weekend security summit, making Canada the only non-European nation represented in talks on how to ensure a possible Ukraine ceasefire actually holds.

Analysts say Trudeau’s visit was meant to maintain Canada’s role in the transatlantic alliance, despite U.S. President Donald Trump pulling back from NATO and blaming Ukraine for Russia’s invasion.

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Trudeau said he would raise matters with the King that are most important to Canadians, adding that Canada’s sovereignty and independence seem to be atop the public’s mind.

The prime minister visited King Charles Monday morning at his Sandringham estate; as is custom, Buckingham Palace did not mention the topics of conversation in its readout.

The King is also set to welcome Trump to Britain at a later date, an invitation the British media has lambasted after a heated exchange in the White House where Trump scolded Ukrainian President Volodymyr Zelenskyy.

Trudeau’s plane left London shortly after noon local time, and he boarded the flight after arriving at Stanstead airport on a British military helicopter.