Islamic State (ISIS) supporters and other jihadis from around the world are using the Austin, Texas-based communication application Zello for planning and executing terrorist attacks in the U.S., the U.K., European countries, Turkey, and elsewhere around the world. On January 30, 2018, it was reported that the perpetrator of the April 2017 Stockholm truck attack had used Zello to communicate with other jihadis immediately after he drove the vehicle into crowds on a main street, killing five people and injuring 14. In March 2017, a Texas-based ISIS recruiter who moderated a Zello channel, instructed followers to kill infidels, and personally approved terror attacks was indicted by a federal grand jury.
The Zello push-to-talk app can be used on smartphones, tablets, and PCs, and is available for Android, iOS, BlackBerry, Windows Phone, and Windows PC operating systems, and for two-way radios. Users can create private or public channels that allow them to easily chat with others and listen to conversations. The main Zello app is free; the [email protected] app is fee-based.
The Zello website states that the app's "advanced encryption ensures all communications are secure." It adds: "Services may disclose personally identifiable information when it's required to comply with law enforcement requests or subpoenas when you violate the Terms of Service." On September 11, 2017, it announced that all private voice messages on Zello on the version released after June 6, 2017 are end-to-end encrypted. The company states that its app has been downloaded 65 million times.
Zello's Russian Connection
The technology that would later become Zello, initially developed in Russia by Alexey Gavrilov under the name Loudtalks, was announced at the September 2007 TechCrunch 40 Mobile and Communications Conference. Zello bought the Loudtalks technology, moved its development team to Texas, and brought Gavrilov on as CTO; under CEO Bill Moore, it was rebranded, other apps were added, and its products were announced in June 2012. Moore is also founder and CEO of the TuneIn radio streaming service; Gavrilov and his team created some popular apps for that service as well.
Zello's Popularity Increased In U.S. During And After Hurricanes Irma And Harvey In Late Summer 2017
When Hurricanes Irma and Harvey struck Florida, Puerto Rico, and the southern Atlantic Ocean in August and September 2017, over a million new users downloaded Zello. It became the top free download in both Apple's App Store and the Google Play store, after gaining fame as the top communications tool of the "Cajun Navy" Harvey rescuers in Houston. "Over one million people have joined [Zello] in the last day, with most coming from Puerto Rico and Florida," Gavrilov said, but went on to warn users that the app was not designed for disaster communications and required either WFi or a cellular data link, despite online rumors to the contrary.
Jihadis Use Zello To Plan Attacks in the U.S., U.K., Germany, Italy, Sweden, Russia, And Elsewhere
Over the past three years, Zello has been at the center of terrorism cases worldwide, as the following example highlights: The Dallas, Texas-based ISIS recruiter Said Azzam Mohamad Rahim, who was moderator of a Zello channel called State of the Islamic Caliphate, told his listeners to kill as many "infidels" as possible with poison, rocks, and trucks, by burning, and by pushing people off buildings. He gave the go-ahead to Salman Abedi, perpetrator of the May 2017 Manchester suicide bombing; in August 2016, Abedi had sought Rahim's approval via Zello, saying: "Sheikh, I live in Manchester, in Great Britain. I live among non-Muslims. I have found work with them. Am I allowed to kill them? Is it permitted to kill them with a bomb?" To which Rahim responded on Zello: "To the boy from Manchester I say, okay, kill them! Show no mercy to civilians."Also receiving instructions from Rahim was Abdulgadir Masharipov, the perpetrator of the New Year's Day 2017 attack at Istanbul's Reina nightclub, in the month preceding the attack.
In March 2017, Rahim was indicted by a federal grand jury for making false statements to federal agents about his alleged support of ISIS. According to the indictment, he had posted his support of ISIS on social media, solicited violence, and praised attacks for which ISIS had claimed responsibility – including the Istanbul nightclub attack and the July 2016 Nice, France truck attack.
Rakhmat Akilov, who carried out the April 2017 Stockholm truck attack, communicated using Zello following the attack. He wrote on the app: "My trousers are burned. I thought it was going to explode but it didn't... Around ten are dead."
Also in April 2017, Italian police arrested a resident of the country who had used Zello to discuss his plans to carry out an attack in Italy. A judge called him "an extremely dangerous subject" who posed a "very high risk of moving on to carrying out series acts of violence." In one Zello message, he had called for "non-believers" to be "roasted on kebab skewers" and fed to dogs.
Tajik national and ISIS member Murodbek Kodirov was arrested in August 2017 for posting a voice message on Zello that included "calls for inciting religious hatred." He had been making plans with another individual, "D. Sharipov," to carry out first an ax attack and then a suicide bombing in a crowd.
Murad Atajev, a Daghestani preacher at a mosque in Berlin attended by Russian-speakers, was arrested in October 2015; he had attempted to recruit ISIS militants, and broadcasts of his sermons were featured on Zello.
MEMRI JTTM Research And Analysis Exposes Extent Of Zello's Popularity Among Jihadis
A September 7, 2016 MEMRI JTTM report revealed that jihadis, ISIS members, and ISIS supporters from around the globe were using Zello. More recently, on April 28, 2017, a link to the pro-ISIS "Zello Channel" group was circulated on numerous pro-ISIS Telegram channels; the link shows that it has nearly 13,000 subscribers.
MEMRI JTTM research over the past two years has discovered a range of ISIS channels in numerous languages on Zello. For example, the Zello "Islamic State channel," which includes "Recruiting new members" in its description, operates in French, Arabic, and Hebrew.
It is notable that all the jihadi Zello groups revealed by MEMRI in the report are apparently still active. The accounts are easily identifiable; they have names such as "The Islamic State" and "The State of the Islamic Caliphate." They have avatars of the well-known black jihadi flag, and of jihadi leaders such as Abu Bakr Al-Baghdadi and Osama bin Laden. They share images of weapons, and threatening messages. All of these are easily recognizable, and Zello should be able to flag them as terrorist content if it wants to.
Zello CEO Requests MEMRI Reports On Jihadis On Zello – But Won't Shut Down Their Accounts
In March 2015, following reports that Zello was being used by ISIS, Zello CEO Moore said that he had not heard that the app was popular among ISIS fighters, and noted, "It's terrible that Zello is used for evil." The company, he said, is putting "a fair amount of effort... into figuring out ways to minimize the app's use by bad guys... so that only healthy conversations can flourish."
The first MEMRI report on jihadi use of Zello, published September 7, 2016, showed that jihadi channels on the platform had thousands of subscribers. Shortly after the report's publication, MEMRI received a request from Moore for a full version of the report and also offered him an opportunity to speak with MEMRI staff about the jihadi content on accounts on the app. Moore ignored this offer, and the content was left on the platform. Later that month, on September 26, MEMRI again contacted Moore to offer assistance, and let him know that the jihadi content was still on Zello. He did not reply, and the content remained. A follow-up MEMRI report, published in April 2017, noted that the content still had not been removed.
In August 2017, Moore publicly acknowledged that Zello was being used by malicious actors, noting: "Oh, it's used for bad, yes. Cartels, gangs, ISIS, and others. Like any communications tool, it's used for good and evil both... It's a net positive, but it's not without risk. It doesn't replace law." Shortly thereafter, in September, he underlined that even though Zello was available to ISIS and other bad actors, he preferred to take a "libertarian" view regarding policing his users – though, he said, he understands the "moral quandary" that this presents.
On February 1, 2018, MEMRI JTTM staff reexamined the accounts and found that most, if not all, remain active.
Zello's Leadership Shows Little Interest In The Fact That The Platform Is Becoming Jihadis' Favorite App – What Can Be Done?
Zello's failure to take responsible action to remove jihadi content on its platform is reminiscent of other tech companies' similar lack of action. In 2010, MEMRI met with representatives from YouTube/Google about such content on their platforms. At that time, I was told that they were not interested in removing it – yet now they do what was recommended. Twitter too brushed off early MEMRI warnings about the jihadi content on it. Now, Zello is ignoring its facilitation of jihad worldwide.
MEMRI's research over the years on jihadi content on these platforms, and repeated attempts to make sure that YouTube and Twitter remained aware of the extent of the problem, contributed to their eventual efforts to remove it. The same can be done for Zello and might compel them to act more responsibly. The Global Internet Forum to Counter Terrorism (GIFCT), a partnership of Facebook, Microsoft, Twitter, and YouTube for collaboration on the issue of terrorist activity online, works to "forge new partnerships" with small tech companies. Joining it would be a good first step for Zello and could steer them to normal industry standards about removing terrorist content.
*Steven Stalinsky is Executive Director of the Middle East Media Research Institute (MEMRI).
 Support.zello.com, accessed February 2, 2018.
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 See MEMRI JTTM report U.S.-Based Walkie-Talkie Encrypted Chat Application Zello Used By ISIS Members And Supporters From Around The World, September 7, 2016.
 See MEMRI JTTM report U.S.-Based Walkie-Talkie Encrypted Chat Application 'Zello' Continues To Serve As A Meeting Place For Jihadists; Calls For Attack On France Transmitted On App, April 28, 2017.
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