The user agreements of both Facebook and Twitter state that they do not tolerate speech promoting violence or terrorism, and vow to shut down accounts that promote terrorist groups like ISIS. Yet despite the continual efforts of social media platforms to remove the accounts, the platforms continue to serve as primary tools for ISIS.

In an effort to counteract the termination of accounts, an ISIS cell calling itself the “Sons of the Caliphate Army” released a 25-minute video threatening the lives of Facebook CEO Mark Zuckerberg and Twitter CEO Jack Dorsey if the accounts continue to close.

The video shows hackers accessing accounts and posting propaganda in support of ISIS, and alleges that the group has gained control of 10,000 Facebook accounts and 5,000 Twitter accounts and turned control over to ISIS supporters.

ISIS maintains a broad presence on social media, with several levels of participants. There are propagandists, who promote the regime and rally supporters; there are recruiters, who identify vulnerable individuals and turn them on to the regime; there are curious individuals, who aren’t fully sold on the cause but are interested in learning more through interactions with other accounts; and there are the operator accounts, for lack of a better term, who serve to connect the web accounts together and monitor who is actually involved.

These operator accounts function like the body of a hydra. When one account is deactivated, the operator locates a replacement account and informs its followers that the individual has returned. This practice enables ISIS accounts to retain their following and maintain an active presence in the community even when the accounts are terminated.

Nevertheless, a study by the George Washington University’s Program on Extremism found that the effort to shut down accounts on social media has had a substantial effect on ISIS’s ability to successfully recruit. Twitter, which is usually mum on the topic, recently stated that in the past six months, 125,000 accounts of ISIS members have been shut down.

It is, however, impossible to completely eliminate the social media presence of terror groups such as ISIS. In such cases, it is imperative that the government make use of the resources available to monitor the activity of terror groups.

This process, however, exists in a legal gray area. Many consider it to be a gross violation of privacy to have government officials policing social media, monitoring accounts, and searching for a proverbial needle in a haystack.

In the case of Twitter, the legality of the process is especially ambiguous. Unless the Twitter account is set to private, the tweets are visible to anyone. It is unclear, however, whether or not the government has the right to search for these tweets.

Nevertheless, if a post has been shared publicly with no restriction placed by the poster on who may view it, government officials should be able to use the information in the post to prevent terrorist activities.

In 2014, the Department of Homeland Security launched three pilot programs to determine the legality of social media monitoring. As of the end of 2015, it still has yet to draw any conclusions on the matter.

Nevertheless, a number of NGOs and research facilities exist that do monitor the social media webs of terrorist organizations. They track the behaviors of the individuals already involved, particularly those involved with recruitment.

Fellows of the George Washington University’s Program on Extremism published in December an extensive study titled ISIS in America: From Retweets to Raqqa, which analyzed the social media recruitment tactics ISIS uses to recruit Americans. The study also delved into tactics for countering violent extremism (CVE) used by a number of local police departments with relatively advanced CVE task forces.

While these departments’ efforts proved effective, they would be even more effective if they were allowed to monitor the publicly shared posts of individuals on social media to prevent crimes.

Until the DHS arrives at its conclusion on the legality of those practices, it is imperative that Facebook and Twitter continue terminating accounts that promote terrorist activities. While the individuals may quickly return to social media, the process breaks the chain of information, slowing down the spread of the radical terrorist ideology of ISIS, even if for only a moment. Despite the threat of death, Zuckerberg and Dorsey must continue to abide by their companies policies and assist in the prevention of terrorism.