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.

“TheInternet 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.