From the report:
The Intelligence Community assesses that the number of former detainees identified as reengaged in terrorist or insurgent activity will increase. A February 2010 review of GTMO detainees’ release dates compared to first reporting of confirmed or suspected reengagement shows about 2.5 years between leaving GTMO and the first identified reengagement reports. Based on trends identified during the past 6 years, the Intelligence Community further assesses that if additional detainees are transferred from GTMO, some of them will reengage in terrorist or insurgent activities.
It is not unusual for former GTMO detainees to communicate with persons in terrorist organizations. The reasons for communication span from the mundane (reminiscing about shared experiences) to the nefarious (planning future terrorist operations). Correspondingly, the Intelligence Community assesses that additional former GTMO detainees will communicate with persons in terrorist organizations. Based on trends identified during the past 6 years, the Intelligence Community further assesses that if additional detainees are transferred from GTMO, some of them will communicate with persons in terrorist organizations.