Twitter and Facebook have recently claimed to be stepping up their fights against extremist content being hosted on their platforms.

Indeed, there is some evidence that certain tactics to counter extremists’ appropriation of mainstream social media platforms — such as Twitter deploying repeat account suspensions — is having an impact on the spread of extremist propaganda.

Earlier this month Twitter blogged about stepping up its fight against “violent extremism” on its platform, saying it has increased the size of the teams reviewing reports of problem content and noting it had suspended more than 125,000 accounts for “threatening or promoting terrorist acts, primarily related to ISIS” since the middle of 2015 alone.

However this more pro-active stance to try to drive ISIS off of mainstream platforms appears to have caught the attention of a group of ISIS supporters who have posted a video online which includes what looks to be a direct threat against Twitter CEO Jack Dorsey and Facebook CEO Mark Zuckerberg, showing their faces being riddled with bullet holes.

The video was spotted by Vocativ, a hybrid media and deep web analysis company, which has posted two screenshots from the video. TechCrunch was also able to find the video online and verify that it contains the threatening sequence.

The majority of the video is given over to depicting a series of Facebook and Twitter accounts apparently hacked by the pro-ISIS group which made the video — and calls itself ‘sons of caliphate army’.

The video also contains a message, written in English, specifically referencing the account bans: “You announce daily that you suspend many of our accounts, and to you we say: Is that all you can do? You are not in our league. If you close one account we will take 10 in return and soon your names will be erased after we delete your sites, Allah willing, and will know that we say is true.”

It’s not the first time Twitter and its CEO have been targeted by ISIS supporters to trying to drive extremists off the platform. Back in March last year a post cropped up online threatening Twitter employees and Dorsey specifically.

According to Vocativ, the video was being hosted on messaging app Telegram. A recent study conducted by an academic from George Washington University which looked at one group of ISIS supporters’ use of mainstream social media suggests Telegram is being favored as a back up for extremists who had been banned from Twitter.

We’ve asked Telegram for a comment on the video being found on its app and will update this post with any response. We’ve also reached out to Twitter and Facebook — neither had responded at the time of writing.

Telegram has made its own counter moves against ISIS propaganda, purging a series of pro-ISIS public channels last November which had been allowing extremists to broadcast pro-ISIS content.

However, according to the George Washington University study pro-ISIS supporters have switched to using Telegram groups and supergroups to communicate en masse. Albeit these channels do not allow for unlimited public reach of their recruitment messages as public channels or mainstream social media platforms can.