Security officials around the world are scrambling to harden so-called :soft targets" -- plentiful and vulnerable civilian gathering sites like night clubs, outdoor festivals and outside stadiums -- in the wake of the latest deadly bombing attack.

Monday’s strike on a large arena concert by U.S. pop star Ariana Grande in Manchester, U.K., left at least 22 dead, including an 8-year-old girl. Manchester Police Chief Ian Hopkins identified the bomber as 22-year-old Salman Abedi, who authorities said died in the attack.

Britain raised its terror threat level to critical on Tuesday, indicating the next attack could come at any moment. Manchester now joins Paris, Brussels, Nice, and Berlin on the list of major European cities recently struck by traumatizing soft-target terrorism.

In Canada, large venues like the Air Canada Centre in Toronto are now promising to even tighter security. And Ottawa is reassuring the public that law enforcement is well prepared to protect the massive crowds expected at the Canada 150 events planned on Parliament Hill on July 1.

“We take Canadian’s security very seriously,” Defence Minister Harjit Sajjan told reporters on Tuesday. “We will continue to do the proper threat assessments, and our agencies are always working 24/7 on this.”

While extra layers of security may feel like a tangible direct response to assuage a jittery public after a gut-wrenching soft-target attack, security experts warn more protections at airports, stadiums, government buildings, city centres, and festivals will only see ever-opportunistic terrorists shift their efforts to the peripheries of those security perimeters.

“Terrorists are morphing their approaches because we’ve morphed our security,” Former Ontario Provincial Police Commissioner Chris Lewis told CTV News on Tuesday. “That is going to continue to happen.”

“Trying to harden everything in our society is not going to work as a strategy in combating violent extremism at these events,” said Stephanie Carvin, an assistant professor at Carleton University specializing in security and terrorism. “We had the attacks on Monday night which had a hardened target, so the violent extremists decided to go for a soft target that was just outside.”

Meanwhile, the challenges facing intelligence agencies continue to grow. Terrorist organizations such as the Islamic State have grown increasingly effective at turning admirers in Europe and North America into attackers via the Internet.

The diversity and sheer number of would-be attackers mean agencies are dividing their attention now more than ever.

“There are no easy answers. There is no age profile. There is no race profile,” said Carvin. “It is really a challenge because there is no type you can refer to.”

Both Lewis and Carvin agree that bolstering the resources of the intelligence community is the only way to prevent terror strikes -- but the way forward is murky.

“The challenge really is to have good community policing, good community intelligence by working to identify problems or an individual of concern before it gets to this level,” said Carvin.

“If you see something, suspect something, know something, say something,” said Lewis. “The life you save might be the 19-year-old brother or cousin that has become radicalized, let alone the innocent kids that were killed in an event like last night.”

How that community-based approach would take shape in Canada is yet to be seen. The Liberal government promised to take steps to develop resources for countering violent extremism in its 2015 election platform.

Carvin argues such an initiative would be inherently valuable, but also costly and rife with legal challenges.

“I think when you put it all together it could be one of the most complex multi-level government programs that the government has actually proposed,” she said. “What do you do with someone you think is going to conduct a violent act, but you don’t know when, you don’t know where. Monitoring these people is extremely expensive and potentially requires a police state.”

With a report from CTV’s Glen McGregor in Ottawa