Twitter staff received death threats from ISIS, admits CEO

Twitter's employees have been threatened with assassination from the group known as ISIS, CEO Dick Costolo revealed in an interview on Thursday.

Speaking with the Aspen Institute's Walter Isaacson at the Vanity Fair New Establishment Summit, Costolo talked about his company's response to ISIS (Islamic State of Iraq and Syria), a militant group that has been occupying areas of Syria and Iraq and is considered a major threat by the US and other countries, which have been battling its forces.

ISIS has been "using Twitter quite effectively" to communicate and spread its message, Isaacson noted. Costolo responded that a public information-sharing tool such as Twitter can be used for good. But he acknowledged that people are also going to "try to use it for nefarious purposes." As such, Twitter has responded in this case by removing the group's accounts as they crop up, citing such accounts as violations of the company's terms of service.

"It's against our terms of service," Costolo said. "It's against the law in many of the countries in which we operate for them to use it to promote their organization. When they do, we find those accounts and we shut them down, and we shut them down quite actively."

In response to the shutdown of those accounts, Costolo said that he personally and all of Twitter's employees have received threats from the group.

"After regularly suspending their accounts, which we've been doing, some folks affiliated with the organization used Twitter to declare that the employees of Twitter and the management of Twitter should be assassinated," Costolo said. "That's a jarring thing for anyone to have to deal with. And I've spent a lot of time talking to the company about it."

Twitter declined to comment on the matter.

Like other social networks, Twitter has to make the sometimes difficult decision whether to suspend or block an account that it believes is in violation of its guidelines. The decision can be difficult because Twitter can open itself up to accusations of blocking the free speech of the account that it suspends. Costolo spoke about the challenge involved in this type of debate.

"It's almost always a debate between two different perspectives about a piece of speech," he said. "One group of users feeling that this type of speech shouldn't be available on the platform, and another group of users saying 'no, no, no, it's very important that that type of speech be available on the platform.'"

In April, Twitter was hit by a ban in Turkey over the posting of tweets containing allegations of government corruption. After two weeks, the ban was lifted by the order of Turkey's constitutional court, which called it a violation of free speech and individual rights.

Update, 9:30 a.m. PT: Adds Twitter declining to comment.