By Alex Altman, TIME

In 2011, the Somali Islamist group known as Al-Shabab took to Twitter. Its official handle taunted the group’s enemies, boasted of battlefield triumphs and shared images from the front lines of conflict zones. It sparred with political antagonists, rattling off missives in grandiose English. The terrorists—like the site’s less murderous users—used Twitter to share news and promote their brand. In 2013, a Shabab account live-tweeted commentary as allied fighters carried out a terrorist attack at a Nairobi shopping mall.

Terrorists love Twitter (TWTR). That includes the Islamic State of Iraq and Greater Syria (ISIS), the Sunni Muslim extremists whom the U.S. is targeting in an expanded military campaign. ISIS has emerged as the most sophisticated group yet at using the service to spread its bloodthirsty message. And when ISIS jihadists and tens of thousands of acolytes swarmed Twitter in recent months, it raised the question of how social media sites should respond when unsavory groups colonize their platform.

There are no easy answers. Social-media networks exist so users can share information; sites like Twitter are neither equipped nor inclined to police large numbers of rogue feeds themselves. And within the intelligence community, there is no consensus on whether the use of sites like Twitter as a propaganda tool hurts or helps U.S. interests.

To some observers, Twitter was derelict in allowing extremist accounts to flourish. “For several years, ISIS followers have been hijacking Twitter to freely promote their jihad with very little to no interference at all,” says Rita Katz, director of the SITE Intelligence Group, which studies jihadi extremists’ behavior online. “Twitter’s lack of action has resulted in a strong, and massive pro-ISIS presence on their social media platform, consisting of campaigns to mobilize, recruit and terrorize.”

Others say it’s not so simple. “There is a case to be made for removing the content or removing the most prolific [jihadist] accounts online. Each time that happens, they had to rebuild their audience. It has a disruptive effect,” says counterterrorism expert Clint Watts, who has studied ISIS’s behavior online. But ISIS accounts may also, in some cases, be a boon to intelligence-gathering efforts. “Their braggadocio tells us what we don’t know about what’s happening in eastern Syria,” Watts says. “In Iraq they show us every one of their successes. There is value in that.”

For that reason, some government officials may prefer the accounts remain open. “There is some value to being able to track them on Twitter,” says William McCants, a former State Department senior adviser who directs the Project on U.S. Relations with the Islamic World at the Brookings Institution. McCants recalls that a U.S. intelligence official described the site as a “gold mine” of information about foreign-fighter networks, better than any clandestine sources. The State Department is using Twitter itself, with a counter-propaganda campaign run through an account, Think AgainTurn Away. It tries to nettle ISIS and neutralize their recruiting.

A Twitter spokesperson declined to comment for this article. The site’s rules prohibit threats of violence, harassment and other abuses, and government agencies or law enforcement officials are able to request the removal of prohibited content. In 2013, it received just 437 such requests from governments worldwide; it received 432 in the first half of this year.