Islamic State (Isis) and its supporters' use of encrypted messaging app Telegram has reportedly reached record highs, eclipsing the terror group's use of other social media platforms, including Twitter.

In the weeks leading up to Christmas, before the tragic Berlin attack, that saw a truck ram into a crowded Christmas market on 19 December, one of IS' known Telegram channels shared messages, calling for volunteers for a holiday killing spree, according to reports.

"Christmas, Hanukkah, and New Years Day is very soon," the message posted on 6 December read, the Washington Post reported. "So let's prepare a gift for the filthy pigs/apes." On Friday (23 December), Isis released a video, which showed chief suspect Anis Amri, who was killed in a shootout in Milan, pledge his allegiance to the terror group.

According to experts, Telegram has now become the top preferred communication platform for the extremist group, partly due to the tech firm's failure in implementing more aggressive measures, now commonly used by its competitors.

According to a report published by Washington-based Middle East Media Research Institute (MEMRI), which tracks terrorists' online communications, Telegram is "the app of choice for many Isis, pro-Isis and other jihadi and terrorist elements." MEMRI researchers classified Isis' recent mass migration to Telegram as one of the most noteworthy developments, in the evolution within the field.

"It has surpassed Twitter as the most important platform," said Steven Stalinsky, lead author of the report. "All the big groups are on it. We see Isis talking about the benefits of Telegram and encouraging its followers to use it."

ISIS use of Telegram eclipses Twitter, making it the ‘app of choice’ for jihadists
According to US authorities, one of the primary reasons for Telegram’s popularity among terror groups is the escalated measures recently adopted by its rival social media platforms IBTimes UK

According to US authorities, one of the primary reasons for Telegram's popularity among terror groups is the escalated measures recently adopted by its rival social media platforms. Twitter and Facebook have cracked down on extremist content. Earlier in the year, Twitter suspended over 235,000 accounts for promoting violence and terrorism.

"Positive steps by Twitter, for example, are part of the reason Telegram is becoming the new thing," said an unnamed senior US official, involved in monitoring Isis' online presence.

"It's alarming because it shows they're really good at adapting to new means," the official said. Highlighting the challenges faced by authorities tasked with preventing attacks, he pointed out that one of the ways to stop attacks involved collaboration between private companies and government officials. Both parties must "figure out how to deny them these capabilities before they even start using them", he said, adding, "That simply hasn't been the case with Telegram."

According to MEMRI researchers, Telegram also provides a meeting ground for "not that smart" wannabe jihadists and experts, who in turn recruit and groom the naive but willing to becoming potential martyrs, putting deadly plans into action.

"The West has been generally two steps behind the jihadis when it comes to cyber," Stalinsky said. "Many people in government are still focused on Twitter, and they need to be. But what we tell them is, 'That's no longer the main story.' "