When four young men made a rushed, late-night knife attack on an elderly Indian visitor to London on Sept. 30, they did not succeed in killing him, but they did reopen one of the messiest incidents in India's past.
The victim was Lieutenant-General Kuldip Singh Brar, who has kept a low profile in India ever since he led the 1984 Indian army assault on the Golden Temple in Amritsar – the most sacred site in Sikhism, where a few hundred heavily armed Sikh militants were holed up and threatening to declare an independent Sikh state, called Khalistan.
Indira Gandhi, then prime minister, was determined to stop them.
Radical survivors of the temple assault vowed to one day revenge themselves by taking the life of Gen. Brar, among others responsible for the attack. Four months after the military action, Ms. Gandhi was murdered by her Sikh bodyguards, setting off bloody riots in which about 3,000 Sikhs were killed. The Indian army chief was assassinated in 1986.
Yet it has been many years since the Khalistani movement carried out an attack like this in India. Indeed, the militants have little purchase among a new generation of Sikh youth there.
However, the London attack on Gen. Brar (who said he had always expected attackers to come for him) raised the spectre that the movement is still alive and perhaps rebuilding in other countries – particularly Canada, where many pro-Khalistan Sikhs immigrated after the Golden Temple clash.
The Indian government highlighted the issue during Prime Minister Stephen Harper's state visit this week, urging that the Canadian government to do more to check the Khalistani movement.
That exchange reflected India's continued unease over what it alleges is diaspora support for militants. However, there is little evidence that even openly pro-Khalistani Sikh communities are engaged in any violent activity.
Mr. Harper assured India that Canada continues to take the issue seriously. But he reminded the government of Prime Minister Manmohan Singh that support for the general idea of Sikh separatism is protected under Canada's free-speech laws.
Experts on terrorism in India track radical Khalistani activity outside the country and say Canada is a hub.
"The diaspora elements are far more radical than anyone in Indian Punjab – and they are being kept alive in fully active groups," said Ajay Sahni, director of the Institute of Conflict Management in Delhi.
Public support of Khalistan gives Sikhs abroad a sense of identity, he said. It is associated with a certain righteousness – a sentiment that is not shared in India.
Today, he added, there is "a significant degree of freedom" for militant activity in Canada and Britain, though both countries' governments do show some concern.
The Indian government continues to be frustrated, though, by the fact that Canadian law enforcement sees militant Khalistanis as an Indian problem – treating it far less seriously than it does Islamist terrorism, for example.
"There is a consistent sense of almost criminal negligence on the part of Canadian law enforcement,"Mr. Sahni said, adding that the perceived failure of the Royal Canadian Mounted Police to stop the 1985 Air India bombing continues to colour the attitude in India.
K.P.S. Gill, the retired director-general of police of Punjab, asserted that Ottawa is naive to let the Khalistani propaganda mill flourish as freely as it does.
"Canada should come down heavily on these guys," said Chief Gill, who oversaw the aggressive law-enforcement campaign that crushed the Khalistani movement in that state in the 1980s and 1990s.
"In a democracy you have to allow expression, whatever the expression is," he allowed. "But there is a threshold, and you should develop the ability to identify that threshold: 'Look, beyond this, now it becomes dangerous.' "
Chief Gill was once seen as an enemy by his own community because of the harshness of the crackdown he oversaw (it was repeatedly criticized by human-rights organizations).
But he said that on a recent series of visits to a gurdwara (temple) in Chandigarh, the capital of the Punjab, people would come to him to touch his feet, a sign of respect, grateful for the era of stability and prosperity he helped to usher in.
"But that change in mindset," he said, "has not been transmitted to the diaspora."
Sikh representatives in Canada, however, insist that the only separatist activity is peaceful, democratic advocacy.
For example, at the Dasmesh Darbar gurdwara in Surrey, one of the largest in Canada, a Khalistani poster hangs in the lobby. In the past, officials there have come under fire for glorifying alleged terrorists on floats and posters at an annual parade.
In an interview at the gurdwara, temple president Gian Singh Gill said the group provides "moral support" to those who want to create Khalistan, and that it is impossible to separate those politics from religion.
"This is a religious place, but when something has hurt your community, it is part of your community," he said.
But he denied that the community has any role in supporting violence. "Our support for that cause is only for people who are working democratically and openly," he said.
"Our position is very clear – that there has been no rise in extremism in the Sikh community," Balpreet Singh, legal counsel for the World Sikh Organization of Canada, said in a recent telephone interview from Toronto.
"There's been nothing on the ground to suggest that radicalism or anything else is on the rise. In fact, the Canadian Sikh engagement with the mainstream community is at an all-time high."
Despite the issue being raised in all bilateral talks between the Canadian and Indian governments since 2007, there has been little or nothing to substantiate the concerns, he added.
"Whenever these allegations come up, it's always been the question of, 'Where's the proof?' "
Both Chief Gill and the Institute of Conflict Management's Mr. Sahni said they believe that the attack on Gen. Brar, while clearly intended as revenge for the Golden Temple assault, was a "crime of opportunity."
That is, it was not plotted and premeditated by a movement, but carried out by a few young men who saw a chance and clumsily seized it.
No similar attack is likely within India, they said, because sentiment has changed, but also because anti-Khalistani policing remains aggressive.
Mr. Sahni said that while Khalistani propaganda and agitation comes predominantly out of Canada and Britain these days, the militants' leaders live in Pakistan.
There, they take advantage of access to the floods of Sikh pilgrims who come to see the birthplace of Guru Nanak, the founder of the religion, bringing funds and potential new recruits.
The Pakistani intelligence services see the Khalistanis as a proxy force in its cold war with India; they arm and fund militant cells, and periodically slip them over the border.
Still, the separatists find few supporters in the Indian Punjab.
The one sore spot is a move under way by the Shiromani Gurdwara Parbandhak Committee (SPGC), also called the Sikh parliament – an elected body that administers the Golden Temple and other gurdwaras – to build an army-assault memorial inside the temple compound.
While SPGC politics are not widely reflected in the community, the Punjab government is not stopping the construction plans, because the committee reliably delivers votes.
Otherwise, a healthy economy, the memory of the bloody cost of the uprising of the 1980s, and the dramatic economic and social changes in India over the past decade have produced a generation that can't even be bothered to talk to about Khalistan.
"There aren't many people who think that's relevant to our lives any more," said Parmeet Singh, a 26-year-old manager with a software company in Amritsar.
"The Khalistan idea, of course, is emotional for people, but practically speaking our future is in India."