The FBI has a new view into what’s happening on Twitter. Last week, the bureau hired Dataminr, a Twitter-linked analytics firm, to provide an “advanced alerting tool” to over 200 users. Twitter owns a 5 percent stake in Dataminr and provides it with exclusive access to the full “firehose” of live tweets, making it a valuable resource for anyone looking for illegal activity on the service. “Twitter is used extensively by terrorist organizations and other criminals to communicate, recruit, and raise funds for illegal activity,” the FBI wrote in a contracting document. “With increased use of...