The Phoenix Project, as described in The Eyes Only Dossier, is a secret American black ops military project aimed at restoring American political and military supremacy in the aftermath of The Pulse.
Manticore supplied the project with four X5 series supersoldiers: Devon/X5-472, Jewel/X5-657, Keema/X5-735, and Lane/X5-600. Alec/X5-494 and Jace/X5-798 were also considered for the project, but were deemed to need further disciplining. Sam/X5-453 was transferred to the industrial espionage section of covert ops.
The four X5s were on deep cover missions for the Phoenix Project when Manticore was destroyed. They remained committed to their missions and unaware of Manticore's destruction. Lane assassinated the Pope several months afterwards and blew himself up when it became apparent that he could not avoid capture. Jewel's last known location is in Moscow, probably on a mission to assassinate the Russian president.