Terrorism online presented a new twist—never before had the United States been involved in a conflict where the enemy could communicate from overseas directly with the American people. And just months before I arrived at the FBI in 2007, working as a special counsel and later chief of staff to Director Robert Mueller, a new online tool named Twitter launched. We had no idea then how much power it would give to online extremists.

https://www.politico.com/magazine/story/2018/11/21/junaid-hussain-most-dangerous-terrorist-cyber-hacking-222643/