Some people are allergic to the T-word. After a lone gunman stormed Parliament Hill last fall, killing a soldier at the National War Memorial, they said it was not possible to conclude that this was terrorism. More likely, the guy just had mental problems. "I think that we're not in the presence of a terrorist act in the sense that we would understand it," said NDP Leader Thomas Mulcair. "I don't think we have enough evidence to use that word."

In the Vancouver Sun, Ian Mulgrew argued that Michael Zehaf-Bibeau was no terrorist. He was a victim. "The vast amount of tax money devoted to his petty crimes would have been far better spent providing him with appropriate psychiatric and social care," he wrote. As for the two people who plotted to bomb the B.C. Legislature, "They, too, seem more sad sack than Satanic."

Now we know better. Mr. Zehaf-Bibeau's self-made martyrdom video, released by the RCMP last week, is chillingly clear about his motives. "This is in retaliation for Afghanistan and because Harper wants to send his troops to Iraq," he said. "We'll not cease until you guys decide to be a peaceful country … and stop occupying and killing the righteous of us who are trying to bring back religious law in our countries." (In a very Canadian touch, he signs off by saying "Thank you.")

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It's easy to see why certain people want to play down the T-word. The terror threat is a potent weapon in Stephen Harper's arsenal. This explains why media reaction to the video has focused not on what it reveals about the shooter's motives, but on how Mr. Harper is shamelessly milking the terror threat to scare the voters into re-electing him. As political strategist Greg Lyle put it in The Globe on Monday, "If the issue is, who do you think is going to be tough enough to deal with those bastards, the answer is going to be Stephen Harper. It's not going to be Justin Trudeau."

It's true that Mr. Harper is overplaying the threat of terrorism. It's also true that plenty of people are underplaying it. Even sad sacks bent on mayhem can get lucky. And it's disturbingly clear that an increasing number of young Canadians – male and female, Muslims and converts, foreign- and Canadian-born – are being caught up in a radical millenarian death cult.

In Toronto, two men, both Muslims, are on trial for allegedly plotting an attack on a Via Rail train. Their motive, according to the evidence, is the same as Mr. Zehaf-Bibeau's: retaliation for crimes against Islam. Their trial heard that the two are also reported to have discussed other options, such as opening fire on Canadians and Jews at the Pride parade. "I want this city, this whole country, to burn," said Raed Jaser, one of the defendants. And: "Everyone is a target, especially Jews." (His lawyer says he's just a con man and didn't mean it.) The other defendant, Chiheb Esseghaier, has refused to defend himself because the only authority he answers to is the Koran.

In Vancouver, John Nuttall and his wife, Amanda Korody, recent converts to radical Islam, are on trial for allegedly plotting to blow up the B.C. Legislature on Canada Day. They wanted to kill "as many [people] as possible," Ms. Korody says on a surveillance tape. "Twenty thousand of these disbelievers, all drunk, and hookers and drunks, and they're all gonna be there," says her husband.

In Manitoba, another convert, a 23-year-old who calls himself Harun Abdurahman is under investigation by CSIS. An active Twitter user, he has advocated butchery and beheadings, and has told journalists that the terror attacks on Parliament Hill and in Quebec were "justified" by Canada's war on the Islamic State. His devastated father, who is a member of the military, is at a loss to explain how he lost his son to radical extremism.

People who say we're overreacting like to argue that you've got more chance of being killed by a moose than by a terrorist. Maybe so, but they are missing an important point. The moose does not want to become a martyr for the Caliphate. A disturbing number of young Westerners do.

The number of extremists is growing across Canada, according to RCMP Commissioner Bob Paulson. So far, we've done a pretty good job of catching the stupid ones. I only hope we catch the smart ones, too. We shouldn't be spooked by terror threats. But we shouldn't be in denial that they're real.