WikiLeaks founder Julian Assange, jailed in Britain this week, has told media contacts he has a large cache of U.S. government reports about inmates at the detention facility at Guantanamo Bay, Cuba, known as GITMO, the last of four major tranches of U.S. government documents which WikiLeaks had acquired and at some point would make public.

“He’s got the personal files of every prisoner in GITMO,” said one person who was in contact with Assange earlier this year…

Several U.S. government sources said there was concern Assange’s material could include highly sensitive “threat assessments” by U.S. intelligence agencies gauging the likelihood that specific inmates would return to militant activities if set free.

These assessments, if published, could prove damaging in a number of ways, including revelations that could theoretically put in jeopardy U.S. intelligence sources and methods.