There's no doubt the country has changed since the terrible killings of two soldiers last week. But will the changes be visible or invisible? Temporary or permanent? Will decisions be made in the grief of the moment that continue to affect the way we live in calmer years?

The day after Corporal Nathan Cirillo was shot and killed while guarding the National War Memorial near Parliament Hill, we were already seeing the changes. The public gallery in the House of Commons was closed, although this is promised to be only temporary. Legislatures across the country were reviewing their security policies. In Toronto, a new announcement played on the transit system's PA: Please be wary of your surroundings and report any suspicious behaviour.

At times like this, it's easy to tip into irrationality, and play to the basest fears of a shaken populace. Doug Ford, running to be mayor of Canada's largest city, announced that the RCMP should be "rounding up" the 90 suspicious individuals on its watch list. "You have to take a hard line. You can't be soft with these people."

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Prime Minister Stephen Harper was more sober and circumspect, but he still used the aftermath of the tragedy to repeat government assertions that stronger anti-terror information-gathering powers are required under the law (and will be part of the government's proposed bill to expand security agencies' reach). "In recent weeks, I have been saying that our laws and police powers need to be strengthened in the area of surveillance, detention and arrest," Mr. Harper told MPs on Thursday.

Such tough talk is likely to be popular at the moment. People are jittery and mourning. Talking about long-term threats to civil liberties will gain you rolled eyeballs. But it's precisely at moments like this – pivotal moments, when things are off-kilter –that we should be talking about how the decisions we make now will be with us far into the future.

That is precisely what our neighbours to the south didn't do, and they're living with the consequences, James Risen argues in his new book, Pay Any Price: Greed, Power and Endless War. The war in question is the war on terror, which Mr. Risen, a Pulitzer-Prize winning security reporter for The New York Times, says has been used as an excuse to conduct a largely secret campaign to undermine Americans' civil rights, spy on their communications and line the pockets of security consultants. As one reviewer said, it reads like a thriller – except, unfortunately, it's not fiction.

Mr. Risen (who is being threatened with jail by the Obama administration for not revealing a source in another story) lays out the ways the war on terror has changed America, without Americans much noticing: The security budget has doubled to more than $70-billion since 2001, much of it falling into the hands of the private contractors, who are "the beneficiaries of one of the largest transfers of wealth from public to private hands in American history." Billions more dollars have simply disappeared.

The domestic eavesdropping program of the National Security Agency, which Mr. Risen first wrote about in 2005, is a direct, law-busting offshoot of the war on terror. George W. Bush's administration did not want it to come to light and put pressure on Times editors. They killed the story twice before it finally ran – and won a Pulitzer for Mr. Risen and co-author Eric Lichtblau. "Of all the abuses America has suffered at the hands of the government in its endless war on terror," Mr. Risen writes, "possibly the worst has been the war on truth."

U.S. politicians have learned "that keeping the terrorist threat alive provides enormous political benefits," he writes. Not just in America, either: In Britain, the ruling Tories have announced a tough-on-terror platform for the next election that will criminalize "extreme" opinions, and jail people who utter them. Canada could follow this lead. As Foreign Policy magazine reported this week, "The terror attacks in Ottawa mean that NSA-style surveillance could be coming to Canada much faster than anyone thought."

Mr. Risen calls this "the cottage industry of fear." Or, as Brian Jenkins of the RAND Corp. tells him, "The object of terrorism is to use violence or the threat of violence to create fear and alarm. And so terrorism has worked. Certainly, we have been the major contributors to that. We have scared the hell out of ourselves."

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That's a valuable lesson, no matter which side of the border you live on.