Here's Hersh's article on Perle.
Here's Tapped on Perle's history and questions of divided loyalty. And they end with an interesting question.

Ed Vulliamy, talking to Eric Alterman about the leaked NSA email, and the arrest of the suspected leaker:

"If charges are made, they will be serious — Britain is far more severe in these matters than the US (so far!). They could result in a major trial and a long prison sentence for the alleged mole. It is also a criminal offence to receive such information in Britain (some of you may recall the ‘ABC’ trial of the 1970s), and this may also become an issue of press freedom. The authors of the piece will defy any attempt by the government to discuss our sources.
It is important that maximum international — as well as domestic British — pressure be brought to bear on the Blair government over this impending case, the prosecution of which will inevitably have a political agenda, and to protect this prospective defendant all we can. Pleading motive will be impossible because there is no defence of justification in Britain. It would be a great help if you would very kindly put your minds to the issue during a spare moment, and think of appropriate people — individuals, concerned organisations, politicians, academics and student or grass roots groups — who might consider making representations to the British government in a letter to the Prime Minister at 10 Downing Street, London, SW1.”