It can’t happen here.

It won’t happen here.

It — almost — did.

But what is “it”?

And how do we protect ourselves against whatever it is?

On Friday night, I was at Scotiabank Centre enjoying the Mooseheads-Shawinigan Cataractes Quebec Major Junior Hockey league game.  During a commercial lull — the game was televised nationally as part of Hockey Day in Canada — I flipped open my Twitter stream: “#Halifax police say they have foiled mass-shooting plot…”

Halifax?

New York… Paris… even Ottawa.

But Halifax?

Police say three people — a 23-year-old woman from suburbia, Illinois, and two young men from middle-class Halifax — had plotted to “kill citizens, and then themselves” at the Halifax Shopping Centre on  Valentine’s Day.

Who were they? What motivated them?

Those questions are still open. We’ve been told the three may have shared a fascination with mass murder — including the infamous 1999 Columbine school shootings — Nazis and Adolf Hitler, and hung out in online mayhem chat spaces. Does that make them terrorists?

The police say no. An RCMP spokesperson told reporters he would classify the plot “as a group of individuals that had some beliefs and were willing to carry out violent acts against citizens,” but their beliefs were “not culturally based.”

That predictably lit up the Twitterverse. Is there a double standard? Muslims are terrorists, while white suburban kids may be “murderous misfits” (in our grandstanding Justice Minister Peter MacKay’s odiously inappropriate phrase), but not terrorists.

Canada’s Criminal Code isn’t much help. It defines a terrorist act as being “in whole or in part for a political, religious or ideological purpose, objective or cause… with the intention of intimidating the public.”

Is someone who commits mass murder for thrills a terrorist? Was Justin Bourque, who targeted police for twisted ideological reasons, a terrorist?  Or should we save our use of that word for Al Qaeda, ISIS militants, Timothy McVeigh… those with not only malice aforethought but also “grander” visions than merely death in a blaze of glory?

How then should we categorize Michael Zehaf-Bibeau, whose Parliament Hill shooting spree seemed inspired by a poisonous cocktail of ideology and mental illness?

The answers matter, both for how we classify these crimes, and also for what kind of laws we need to combat them.

But those discussions are for another today.

Today, we simply say thank you to whoever tipped off police for whatever reason, and to the police for reacting quickly and well to prevent a tragedy.

Because it can happen here.