U.S. officials say the Internet was both the inspiration and the downfall for the group arrested in Canada.
Like the terrorists behind the 2004 Madrid train bombing, the Canadians are thought to be part of an emerging trend with no direct connections to Osama bin Laden and al-Qaida.
"These groups aren't being supported by a central hub that's taking care of their funding, their equipment, their bombing expertise," says the FBI's John Miller. "They're putting themselves together in the field and doing it with whatever resources they can generate on their own."
The net around the Canadian cell began to tighten in October with the arrest in London of a man suspected of operating a terrorist Internet site, one that investigators say the Canadian group was using, too.
The FBI says two Atlanta-area college students, arrested two months ago, were also using it and took the bus to Toronto a year ago to meet some of the Canadians.
In on those same Internet conversations, U.S. officials say, was an Islamic extremist in Sarajevo, who was arrested with suicide bomb vests.
The former top counterterrorism official for New York says the Internet provides potential terrorists with radical inspiration, bomb instructions and a way to communicate.
"The Internet is like the new Afghanistan," says Micheal Sheehan, an NBC News terrorism expert. "It's the way radicals can get together when it's more difficult for them to travel and find sanctuary."
Monday night, officials say this case shows that police and intelligence agencies from several countries are learning to work together to connect the dots worldwide.