NEW YORK - The Internet is the new battleground against Islamist extremism because it provides ideology that could radicalize Westerners who might then initiate home-grown attacks, New York police commissioner Raymond Kelly said on Wednesday.

"The Internet is the new Afghanistan," Kelly said, as he released a New York Police Department (NYPD) report on the home-grown threat of attacks by Islamist extremists. "It is the de facto training ground. It's an area of concern."

The report found that the challenge for Western authorities was to identify, pre-empt and prevent home-grown threats, which was difficult because many of those who might undertake an attack often commit no crimes along the path to extremism.

The report identified the four stages to radicalization as pre-radicalization, self-identification, indoctrination, and jihadization, and said the Internet drove and enabled the process.

Radicalization could be triggered by such things as the loss of a job, the death of a close family member, alienation, discrimination, and international conflicts involving Muslims, said the report by senior NYPD intelligence analysts.

"Much different from the Israeli-Palestinian equation, the transformation of a Western-based individual to a terrorist is not triggered by oppression, suffering, revenge or desperation," it said.

"Rather, it is a phenomenon that occurs because the individual is looking for an identity and a cause and unfortunately, often finds them in extremist Islam," said the report "Radicalization in the West: The Home-grown Threat."

While the September 11 strike on the United States by Osama bin Laden's al Qaeda network was planned overseas, the report said the attacks had helped proliferate and accelerate radicalization, especially in the West.

"More importantly, 9/11 established the current trend of committing an act in the name of global jihad as a natural culmination of full radicalization and the ultimate responsibility for the fully radicalized jihadist," it said.

But starting the radicalization process does not mean everyone will progress to "become a terrorist."

"Individuals who have been radicalized but are not jihadists may serve as mentors and agents of influence to those who might become terrorists of tomorrow," said the report, which analyzed five home-grown U.S. attack plots.

It says Europe's failure to integrate second and third generation immigrants into society, both economically and socially, had left young Muslims more vulnerable to extremism.

While economic opportunities in the United States are better and the country's Muslims are more resistant to Islamist extremism, they are "not immune to the radical message."

"The powerful gravitational pull of individuals' religious roots and identity sometimes supersedes the assimilating nature of American society," the report said.