A Twitter account linked to the Islamic State, the extremist group also known as ISIS or ISIL, called out specific assassination targets in the U.S. for the first time Monday — specifically, Twitter employees. But the social media company isn't freaking out just yet. 
 
 "The time has arrived to respond to Twitter’s management by directly attacking their employees and physically assassinating them," read one of several threatening tweets from an account named @Dawlamoon. It added that the attack would be carried out "by the sleeper cells of death." 
 
 A later tweet stated: "Every Twitter employee in San Francisco in the United States should bear in mind and watch over himself because on his doorstep there might be a lone wolf assassin waiting." All the tweets were written in Arabic, accompanied by a hashtag that translates to "the concept of lone wolf attacks." 
 
 The @Dawlamoon account is linked to a Jerusalem-based group called Al Nusra Al Maqdisia, which is linked to and frequently mentioned in Islamic State forums, according to a report from Vocativ. Its exact connection to the Islamic State remains unknown. 
 
 Twitter suspended the @Dawlamoon account, which had more than 3,000 followers, after the death threats were issued Monday, and opened an official investigation. 
 
 "Our security team is investigating the veracity of these threats with relevant law enforcement officials,” a Twitter spokesperson told Mashable. 
 
 Twitter has been shutting down ISIS-related accounts repeatedly over the last few months, but new ones are continually cropping up. The group has also been using the social network Diaspora, initially established as a rival to Facebook. A fugitive American citizen named Ahmad Abousamra is wanted in connection with the group's social media efforts. 
 
 Twitter would not say whether security at its headquarters had been beefed up as a result of the threats. ||||| Twitter founder Jack Dorsey has been threatened with death because the company blocks ISIS social media accounts, BuzzFeed first reported on Sunday. 
 
 The social media site has suspended users linked to terrorism in the past. 
 
 The Islamic State threat went live on pastebin 15 hours ago, and calls on jihadists across the world to rally in a fight against Twitter. Pastebin is an anonymous online site favoured by coders. The page basically declares war on Twitter. 
 
 BuzzFeed reports that the post has now been shared by ISIS supporters, but its exact author hasn't been identified yet. So far the page, which features an image of the Twitter logo and what appears to be Dorsey's face covered by a gun target symbol,has had around 1,750 views. 
 
 The post is written in Arabic, though Google translate (not entirely accurate) paints a basic picture of what it says. One extract reads: "Jack helpless when their necks officially become a target for the soldiers of the Caliphate and supporters scattered among your midst." The word Caliphate has both religious and political connotations and describes a strict Muslim government led by a Caliph, a successor to the prophet Muhammed. 
 
 Later in the post, the writer talks about a "media war" and says that by stopping ISIS and its supporters from tweeting their messages, employees are "preventing the delivery of the holy mission to the world." At the time of writing, Dorsey's Twitter feed suggests he's not acknowledged the attack. 
 
 Twitter told us that it is looking into the threats. "Our security team is investigating the veracity of these threats with relevant law enforcement officials," a spokesperson said in an email to BI UK. 
 
 
 
 It's not the first time Twitter employees have been threatened by ISIS. CEO Dick Costolo has said in the past that the militants have spoken out about being prevented from spreading their jihadist movement online. Costolo has talked about "balancing free speech and open speech with wider concerns." 
 
 Business Insider has contacted Dorsey/Twitter for comment and will update this post if/when we get a response.
– ISIS has got a social media problem and it seems to think it can kill its way out of it. A Twitter account linked to the extremist group has called for the assassination of Twitter employees, apparently in response for the site's attempts to shut down ISIS accounts, reports Vocativ. "The time has arrived to respond to Twitter’s management by directly attacking their employees and physically assassinating them," read one of the threatening tweets from a Jerusalem group that has pledged allegiance to ISIS. "Every Twitter employee in San Francisco in the United States should bear in mind and watch over himself because on his doorstep there might be a lone wolf assassin," read another Arabic-language tweet from the account, which has now been shut down. A spokesperson for Twitter—which shuts down ISIS accounts as soon as they surface—tells Mashable that the company's "security team is investigating the veracity of these threats with relevant law enforcement officials." The company won't say whether it has boosted security at its headquarters in San Francisco, reports the San Francisco Chronicle.