The leaked NSA Inspector General report detailing the history of the domestic spying program reveals that the NSA resurfaced a 1999 plan to "perform contact chaining on metadata it had collected." The report explains: "Analysts would chain through masked US telephone numbers to discover foreign connections to those numbers, without specifying the US number involved." Iin December 1999, th e DOJ had declared this type of searching illegal under the Foreign Intelligence Surveillance Act (FISA) when applied to metadata belonging to US persons becuase it was considered "electronic surveillance" under FISA.