An explosive allegation from Canada that the Indian government may have been behind the assassination of a Sikh separatist activist on Canadian soil has triggered a huge diplomatic row and sent relations between the two plummeting.
It all started on Monday, when Canadian Prime Minister Justin Trudeau claimed he has credible information linking India to the killing of prominent Sikh leader Hardeep Singh Nijjar.
Canada's allegation outraged India, which has vehemently denied the claim, calling it "absurd and motivated".
Both Canada and India acted swiftly to expel senior diplomats in reciprocal moves earlier this week. And on Thursday, India's foreign ministry responded by temporarily suspending visa services for Canadian citizens over what it said are "security threats" against diplomats in Canada.
Experts say the falling out raises the prospect of an unprecedented rift between two key partners of the United States, and puts other major Western countries in an uncomfortable position.
Here's what you need to know.
What are the two sides saying?
Trudeau claimed in Parliament on Monday that Canadian authorities had been investigating "credible allegations" of a potential link between "agents of the government of India" and the killing of Nijjar, a Sikh Canadian citizen who was gunned down by masked men in June.
Canada's foreign affairs minister Melanie Joly subsequently said that Ottawa had expelled an Indian diplomat, whom she described as the head of the Indian intelligence agency in the country, as a "consequence".
India responded hours later by rejecting Trudeau's allegations, accusing Canada of harboring terrorists and claiming its inaction against extremists had been a "long-standing" concern. It also expelled a senior Canadian diplomat from the country.
Nijjar's death in June shocked the Sikh community in Canada, one of the largest outside India with more than 770,000 members.
Following Trudeau's comments, two Sikh community groups in Canada – the British Columbia Gurdwaras Council and Ontario Gurdwaras Committee – urged the Canadian government to "immediately suspend all intelligence, investigative and prosecutorial cooperation with India".
"Canada's comprehensive response must reflect the gravity of India's role in the premeditated murder of a Sikh dissident living in Canada," the groups added in a joint statement.
On Tuesday, Trudeau doubled down on the allegations. He said Canada wasn't trying to "provoke" India or "escalate" the situation, but was "simply laying out the facts" adding that his government will "follow the evidence and make sure that the work is done to hold people to account".
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Who was Hardeep Singh Nijjar?
Nijjar was an outspoken supporter of the creation of a separate Sikh homeland known as Khalistan, which would include parts of India's Punjab state.
The Khalistan movement is outlawed in India and considered a national security threat by the government. A number of groups associated with the movement are listed as "terrorist organisations" under India's Unlawful Activities (Prevention) Act (UAPA).
Nijjar's name appears on the Home Ministry's list of UAPA terrorists and in 2020, the Indian National Investigation Agency accused him of "trying to radicaliSe the Sikh community across the world in favoUr of the creation of 'Khalistan'", adding that he had been "trying to incite Sikhs to vote for secession, agitate against the government of India and carry out violent activities".
Nijjar's friend and former lawyer, who also appears on India's UAPA wanted list, said Nijjar was warned at least three times by Canadian authorities including the Royal Canadian Mounted Police about threats to his life.
Gurpatwant Singh Pannun told CNN that Nijjar was asked to be careful and avoid giving "big talks" or he would be targeted. CNN has reached out to the Royal Canadian Mounted Police.
Pannun, who faces multiple charges from the Indian government, runs a New York-based outfit called "Sikhs for Justice," which has held referendums for a separate Khalistan state. The organisation is considered unlawful in India, where its website is not accessible.
Canadian police have not arrested anyone in connection with Nijjar's murder. But in an August update, police said they were investigating three suspects and issued a description of a possible getaway vehicle.
Can relations return to where they were?
Relations between the two countries have been tepid for several years and Canada's allegations against the Indian government has further soured things.
Harsh Pant, vice president of foreign policy at the New Delhi based think tank Observer Research Foundation, called the situation "quite extraordinary".
"Friendly nations don't do this to each other," he said.
"The challenges (that arise from this) are something to be seen because I don't see any light, at least in the short term, at the end of the tunnel."
Negotiations for a trade deal between the countries have been paused due to issues "of serious concern", India's commerce and trade minister said, according to local reports.
When Modi hosted the Group of 20 (G20) leaders in New Delhi this month, he did not meet Trudeau one-on-one but on the sidelines of the summit, where the Indian leader "conveyed our strong concerns about continuing anti-India activities of extremist elements in Canada", according to the Indian government.
Tensions have been "simmering under the surface for a while", Pant said.
When Trudeau visited India in 2018, his calendar, which was light on diplomatic meetings, was seen by many as a "snub" from New Delhi. A year earlier, the Canadian leader had been seen at a Sikh event in Toronto where separatist flags and posters depicting an extremist Sikh leader killed in a 1984 Indian Army operation were displayed.
In its statement on Tuesday, the Indian government said: "That Canadian political figures have openly expressed sympathy for such elements remains a matter of deep concern."
On Thursday, India's Ministry of External Affairs said it was halting issuing visas to Canadian citizens, blaming "security threats".
"The issue is of incitement of violence, the inaction by the Canadian authorities, the creation of an environment that disrupts the functioning our high commission and consulates, that's what's making us stop temporarily the issuance of visas or providing visa services," the ministry's spokesman, Arindam Bagchi, told reporters in New Delhi on Thursday.
Despite all this, Michael Kugelman, director of the South Asia Institute at the Wilson Center, said he thinks the "relationship is salvageable".
"Canada is a top investor in India and also (has) a very large Indian diaspora in Canada," he said.
"And people to people relations are very strong on the whole."
How have others responded?
Canada's allegations come days after Modi hosted world leaders including US President Joe Biden, British Prime Minister Rishi Sunak and Ausralian Prime Minister Anthony Albanese for the G20 summit in New Delhi.
Each of those countries has a sizeable Sikh population and are keen for warm relations with New Delhi, in part as a buttress against the growing assertiveness of China.
However, those three key allies of Canada issued statements that indicated some support for Trudeau's decision to go public with his concerns.
The White House is "deeply concerned" about the allegations, National Security Council spokesperson Adrienne Watson said, adding it was "critical that Canada's investigations proceed and the perpetrators be brought to justice".
A spokesperson for Foreign Minister Penny Wong said Australia is also "deeply concerned."
"We understand these reports will be particularly concerning to some Australian communities," They said in a statement.
"The Indian diaspora are valued and important contributors to our vibrant and resilient multicultural society, where all Australians can peacefully and safely express their views."
Meanwhile, a spokesperson for the British prime minister said, "It's right that the Canadian authorities are looking into (the matter), but I'm not going to get ahead of that work that needs to take place now."
Kugelman said Canada would've "gone through a very extensive process" to investigate the allegations.
"It counts on very close intelligence relationships with the US and the UK and Australia among others," he said.
Kugelman added it was "notable" that Canada is a member of the so-called Five Eyes, an intelligence pact that also includes the United States, Britain and Australia and New Zealand.
"Indeed, one would think that Canada would've had to undertake a significant, careful investigation before being willing and comfortable to make these allegations public," he added.
