Ottawa's decision Monday to expel India's top envoy and five other diplomats is just the latest development in tensions that have simmered for months between the two countries.
Here's a look at what's driving the chill between Canada and India.
Why is India mad at Canada?
India is a staunch opponent to the Khalistan separatist movement, in which some Sikhs advocate for an independent state called Khalistan to be carved out of Indian territory.
India says the prospect is unconstitutional and threatens the country's national security. Ottawa has long stressed that it upholds India's territorial integrity but won't crack down on freedom of expression in Canada.
Khalistan supporters in Canada occasionally organize rallies and what they call referendum, which get little mainstream media attention in Canada but are the subject of emotive news reports in India. Organizers say India has persecuted them through decades, a claim New Delhi rejects.
Some Sikh temples have been found to be openly venerating people connected with acts of violence like the 1985 bombing of an Air India flight, which is the deadliest terrorist attack in Canadian history.
Did India kill a Canadian?
In September 2023, Prime Minister Justin Trudeau announced that Canadian intelligence services are investigating "credible" information about "a potential link" between India's government and the killing of Sikh leader Hardeep Singh Nijjar in British Columbia.
New Delhi initially outright denied any involvement, before shifting to saying that extrajudicial killings are not state policy.
Meanwhile, American authorities last November unsealed an indictment alleging a murder-for-hire plot by an Indian national. The court file alleges an Indian government employee directed the attempted assassination in the United States, and spoke about others, including Nijjar's killing in Canada.
This past May, police in Edmonton arrested three Indian nationals and charged them with first-degree murder and conspiracy to commit murder in Nijjar's death.
India maintains that Canada has never shared evidence of the country's involvement in the homicide, though Trudeau said Monday that Canadian authorities shared this information with their Indian peers over the weekend.
Since last autumn, India has temporarily suspended visa services for Canadians. It also withdrew diplomatic immunity for most of Canada's envoys, which Ottawa said forced it to bring home most of its diplomats.
Is India important?
In November 2022, Canada declared India "a critical partner" in its Indo-Pacific strategy, calling for a trade agreement, more work exchanges and partnerships in renewal energy.
Canada is among the countries that have spent years trying to court New Delhi amid growing concerns about China. Ottawa has said that India is key to promoting democracy and pluralism worldwide.
India relies on Canada for large imports of lentils and potash, and is a popular destination for students looking to study abroad in both advanced research degrees and vocational colleges.
Until September 2023, Canada and India had been in numerous rounds of high-level negotiations for a trade deal restricted to key industries, years after both countries abandoned an attempt at a comprehensive deal. Canada paused the latest negotiations shortly before making public its concerns about the Nijjar case.
Is this a political spat?
Indian Prime Minister Narendra Modi's government has argued that Trudeau hasn't taken the issue of Khalistan separatism seriously.
In 2018, Trudeau's visit to India caused controversy when it emerged that his delegation had invited Jaspal Atwal — a B.C. Sikh convicted of attempting to assassinate an Indian cabinet minister in 1986 — to two events with Trudeau.
In a background briefing arranged by the Prime Minister's Office, a government official told journalists that Atwal's presence had been arranged by factions within the Indian government who wanted to sabotage Trudeau's visit due to the Khalistan issue.
A year ago, Indian Foreign Affairs Minister Subrahmanyam Jaishankar suggested the latest rift comes down to issues his government has with Canada's Liberals.
"The problems we have are with a certain segment of Canadian politics, and the policies which flow from that," he said.
What happened on Monday?
On Monday, the RCMP warned the public about a rash of crimes including murder, extortion and coercion linked to Indian government agents.
The RCMP and other Canadian officials confronted India earlier this past weekend, and when New Delhi refused to co-operate, Ottawa ordered six Indian diplomats to leave Canada. India has similarly expelled six Canadian diplomats.
This report by The Canadian Press was first published Oct. 14, 2024.