Joel Brenner, a former US counter intelligence official said about the news,
“This is potentially devastating from a counter intelligence point of view,” “These forums contain decades of personal information about people with clearances . . . which makes them easier to recruit for foreign espionage on behalf of a foreign country.”
Sir Tim Berners-Lee has previously highlighted the dangers of blackmail if foreign spy agencies get hold of data on persons with access to national security information, although in the context of the retention of web surfing and phone records – see here.