This week in New York, as he listened to questions from reporters, Canadian Prime Minister Justin Trudeau’s reliable smile began to fade.

Unsurprisingly, nearly all the questions were about India and the shocking allegation made by Mr Trudeau earlier in the week: there was credible evidence the Indian government had participated in the extrajudicial killing of a Canadian citizen on Canadian soil, a Sikh activist whom India has accused of terrorism.

Delhi has denied having anything to do with the murder.

Speaking slowly, carefully, the prime minister stuck closely to his talking points. “We’re not looking to provoke or cause problems,” he said. “We’re standing up for the rules-based order.”

But where, several reporters asked, were Canada’s allies? “So far in time,” one journalist said to Mr Trudeau, “you seem to be alone”.

In the public eye at least, Mr Trudeau has appeared to be left largely on his own as he goes toe to toe with India, one of the world’s fastest-growing economies, with a population 35 times bigger than Canada’s.

In the days since the prime minister made the explosive announcement, his allies in the Five Eyes intelligence alliance provided seemingly boilerplate public statements, all stopping far short of full-throated support.

UK Foreign Secretary James Cleverly said his country took “very seriously the things that Canada are saying”. Using nearly identical language, Australia said it was “deeply concerned” by the accusations.

But perhaps the most deafening silence came from Canada’s southern neighbour, the United States. The two countries are close allies, but the US did not speak up with outrage on Canada’s behalf.

When President Joe Biden publicly raised India this week, while speaking at the UN, it was not to condemn, but to praise the country for helping to establish a new economic pathway.

Mr Biden’s National Security Adviser Jake Sullivan later denied that there was a “wedge” between the US and its neighbour, saying Canada was being closely consulted. But other public statements were tepid, more nods to “deep concern”, coupled with affirmations of India’s growing importance to the Western world.