How real is the threat of a cyber attack?

WATCH: Two leading cyber security experts break down the cyber security threats and the potential impact of a cyber attacks in Canada and the United States.

It’s an invisible threat and the results can be disastrous.

Here at home, the watchdog monitoring cyber threats says the government faces millions of cyber intrusion attempts every day.

The head of the U.S. Cyber Command, Admiral Michael Rogers, told Congress last month the government, private sector, and academia will all have to work together to prevent the next dramatic attack — or risk disaster.

More information stolen, more sensitive documents leaked, even the potential to shut down a country’s basic infrastructure.

WATCH: The West Block host Tom Clark explains the threat of cyber attacks against individuals, companies and countries.

China, Iran and Russia, all have the potential to effectively shut down North America, Rogers said.

“It might be time to add the North Koreans to that list,” said James Lewis, a cyber-warfare expert at the Centre for Strategic and International Studies. “The electrical grid is not as well protected as we might hope … And these countries have the ability to disrupt services, to turn off electricity, and perhaps even at the high end, cause physical destruction.”

Dave Lewis, of Akamai Technologies, specialising in cyber security, however, said the country’s concern should be placed elsewhere.

“I think the real concern is actually more along the lines of the infrastructure that we currently have in place and something along the lines of a very large storm causing more damage,” he said. “I would be more concerned about that than I would about a cyber-attack. That being said, there is a lot more than can be done to better secure the power systems in Canada.”