In the past, Al Qaeda and its affiliates, which have broken with the Islamic State, “saw the Internet as a place to disseminate material anonymously or meet in ‘dark spaces,’ ” Mr. Hannigan wrote, while the Islamic State “has embraced the web as a noisy channel in which to promote itself, intimidate people and radicalize new recruits.”The opinion article by Mr. Hannigan referred specifically to messaging and social media sites and apps such as Twitter, Facebook and WhatsApp.“There is no need for today’s would-be jihadis to seek out restricted websites with secret passwords: They can follow other young people posting their adventures in Syria as they would anywhere else,” he wrote.