The moment Prime Minister Stephen Harper decided Canada would host this week's G20 meeting, Toronto was fated to become a fortified city.
Police and military leaders decided that Muskoka, host of the G8 summit, could not also accommodate the G20 to follow. So they were forced to accept that dozens of world leaders would be crammed into the densest corners of Canada's largest city - and that, to protect them, authorities would need to install three-metre-high fences and summon thousands of police, leaving residents bemused and bothered.
This is the new reality of hosting global summits in an urban setting, when the only thing officials agree on is that they can't spend too much to safeguard against the nightmare of playing host to an international incident.
"It's damned if you do, damned if you don't," said former top Mountie Norman Inkster, arguing today's realities bear no resemblance to the last time Toronto hosted such a summit - when he was commissioner in 1988. "This is an entirely different scene now."
The ranks of world leaders and entourages attending such summits are swelling to the point that smaller communities cannot accommodate them. And the decision to host not just the G8 but the G20, with its attendant entourage, is about more than the mere addition of numbers - it's about adding group of countries with diverse political baggage, which in turn multiplies the flanks authorities have to protect in one of the world's most multicultural cities.
"The ethnic mix that makes Canada the wonderful country it is brings with it some of its challenges," Mr. Inkster said.
On top of that, terrorist threats are becoming harder to predict, meaning organizers are faced with a cascading series of best-bad-option choices. "What is the limit to the expenditures necessary to safeguard against any potential risk? It's a bottomless barrel of demands," said George Rigakos, a Carleton University professor who researches how states police dissent.
One security source says the thinking is not that abstract. If, say, Indian Prime Minister Manmohan Singh wanted to visit Toronto's Little India, could he be at risk from extremist South Asian groups? International obligations compel Canadian security forces to protect "internationally protected persons" like Mr. Singh - and the dozens of other world leaders who are coming.
Ottawa's estimated $930-million security cost announced this spring outraged taxpayers, who never contemplated a bill of that magnitude when Mr. Harper's government first won the right for Canada to host the 2010 G8 meeting.
But "I think it's a bargain, quite frankly, and you can quote me on that," said John Kirton, a University of Toronto professor and booster of such summits. People have to understand, he said, that the meetings are two very big summits, not one. "This is probably the only time in world history where we'll ever have a G8 summit and a second separate G20 summit taking place so close in time and space," he said.
Mr. Harper essentially doubled down by splitting the summits. Were there better options?
By all accounts, Huntsville was already hard-pressed to host a G8 meeting. Dispersing dozens of world leaders around cottage country for the subsequent G20 was a non-starter for security reasons, experts say. The rural venue could have been abandoned altogether in favour of urban Toronto, but myriad spending commitments had already been made for the G8.
And Mr. Kirton, the director of the G8 Research Group at the University of Toronto, argued the G20 had to go to downtown Toronto's Metro Convention Centre - the site of the 1988 G8 summit. He dismisses critics who suggest the empty Canadian National Exhibition grounds would have been a better option, as there are few hotels nearby.
But even accepting the convention centre was the right venue, why is it surrounded by high fences and phalanxes of police? Officials have trouble articulating their precise fears.
The sobering reality is that no one really knows what the biggest threats are any more. This year, Americans are reeling from attacks no one saw coming - not President Barack Obama, nor his multibillion-dollar intelligence community. Two homegrown U.S. terrorists have targeted New York. A "lone wolf" gunman shot up a Texas barracks. A Nigerian tried to blow himself up on a transatlantic flight. And an al-Qaeda double agent's suicide bomb killed several U.S. agents in Afghanistan.
Authorities are skittish because the unknown unknowns have multiplied. Jarret Brachman, a counterterrorism expert at North Dakota State University, says a more amorphous threat means authorities have to "double down" on security. "You need to spend disproportionately to the threat," he said.
To add to the complications, the hasty decision to relocate the summit to Toronto meant thousands of police had to be hired in a hurry. Federal negotiators ponied up quickly for provincial and municipal cops to join the fold, and rank-and-file police are notoriously hard negotiators. In extreme cases, overtime costs for senior officers could approach $100 an hour.
Some experts point out that Canada's spending is not that out of line with some past summits - a G8 that Japan hosted a decade ago is said to have cost $1-billion.
That's why not everyone scoffs at Canada's security. "That makes sense," said David Tubbs, a former FBI official who has helped co-ordinate security for the 1999 World Trade Organization conference in Seattle and the 2002 Winter Olympics in Salt Lake City. "… If you're going to have a big event, you have to have the security."
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