FILE - In this Feb. 11, 2015, file photo, Sen. Dianne Feinstein, D-Calif., speaks during an interview with The Associated about the CIA torture report, in her Capitol Hill office in Washington. Social media giants including Twitter, Yahoo, Facebook and Google are pushing back against Senate legislation that would require them to alert federal authorities of any terrorist activity. The Senate Intelligence Committee has included the requirement in a broader intelligence bill. The House didn’t include a similar provision in its bill. (AP Photo/J. Scott Applewhite, File)

Could Twitter stop the next terrorist attack?

Popular social media sites have become instrumental in helping terrorist groups expand their influence, despite widespread industry policies against posting or promoting terrorist-related content.