Public spaces are tricky to police and attackers know to exploit it

It's a reaction that's becoming all too familiar: In the wake of an attack, there comes thepromise to beef upsecurity.

After Monday's bombing outside anAriana Grande concert in Manchester, U.K., a number of event venues around the world were swift to say they were upping their own measures, including Winnipeg's MTS Centre and Toronto's Air Canada Centre.

The ACC which will host back-to-back shows by Toronto R&B star The Weekndlater this week says it is boosting the number of security staff on its grounds, while the MTS Centre says it will employ a bomb-sniffing dog.

Yet curbing attacks like the one in Manchester may prove to be a near-impossible task, says Waterloo, Ont.-based security consultantTodd Gottschalk, who hasrun security for Cirque duSoleil tours,bandsand music festivals.

"You can't guarantee 100 per cent that this is not going to happen," he said of the ISIS-claimed suicide blast, which killed 22 people. "The most you can do is limit your liability."

The bomb went off just outside the arena, when the crowd was leaving the show a so-called soft target that is tricky to police.

Gottschalksuggests having more police and security roam these vulnerable public spaces, looking for the unusual. If something appears suspicious, Gottschalk said security should "be able to pick up on that right away."

Though he admits that's likely tough when it comes to suicide attacks.

"You can never judge somebody's state of mind," he said."Suicide bombers are very troubled people Nothing will stop that cause."

'Not a matter of tightening up tonight'

Entertainment venues have been targetedbefore: Gunmen inside the Bataclan concert hall in Paris killed almost 90 concertgoers in 2015, while 39 people died in Turkey from a gunman who stormed an Istanbul nightclub last New Year's Eve.

But theheightenedsense of security that comes after theseattacks often fades away, Gottschalksaid, until another one happens. "It's not a matter of tightening up tonight. It should [have been]at that time."

He said it iscrucial for eventsto have up-to-date crisis control and emergency evacuation plans to serve as some sort of guideshould something happen.

As the investigation into the attack unfolds, more details will be learned about how it happened.

Steve Summerville, a former Toronto policestaff sergeant who trains and consults venues on security matters, says the ManchesterArena's security isn't necessarily to blame.

"There is no suggestion that the venue for the [Ariana] Grande concert did anything wrong. Nothing occurred inside," he said."I would assume that they had checks and balances to get in."

The risk, he said, is at the event's perimeter, where security doesn't always extend.

Summervillehas co-ordinated large-scale security operations including Toronto's massive 2003SARS benefit concert and says there's simply not enough security or police to prevent every presumed threat.

"You cannot prevent ... 2.5 million people from accessing a public street," he said, referencing the population of Toronto.

"There are systems in place to create a reasonable level of protection but there would be no way to ensure [nothing happens] without usurping people's rights."

'Do not let it deter you'

Attackers exploiting the areasjust outside of the secured barriers is becoming an established tactic: Similar situations happened with the Boston Marathon bombings, which took place close to the finish line, and with last year's blasts at Brussels' Zaventem Airport and Istanbul'sAtaturk Airport.

In situations like these, it is"extremely difficult to do anything at all" to avoid the threatentirely, says Michel Juneau-Katsuya, a former senior intelligence officer with CSIS.

"[ISIS] have developed this strategy, basically," he said. "Anywhere, any time and anyway, when there is a crowd, there is a potential target."

"It's so troubling," adds Gottschalk. "Entertainment is there to provide joy."

Some musicians have cancelled their concertsin wake of Monday's bombing. But for others, the show goes on. And if the show is a go, Gottschalksays eventgoers shouldn't be afraid toattend.

"Do not let it deter you from enjoying your life This is what these people want," he said, referring to the suicide bomber. "Let them see that it doesn't bother you."