So long as the classified information isn't to do with covering up torture and so forth.

If it's a case of some needing to protect their identity because of risk to themselves or their family etc there are ways of ensuring that is done within a normal court structure.
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Iraqi authorities believe al Qaeda in Iraq is behind the violence. Quite possibly - but since the occupation the Christian minority in Iraq (which has longer historical roots in the country y than the Muslim majority) has been mostly driven out, and many have been killed. And most of this hasn't actually been the work of Al Qaeda, though of course they've done their bit. It was a direct result of the sectarianism unleashed by the invasion. The invasion was a complete disaster for Iraqi Christians. And not least because it gave Al Qaeda the opportunity to move in and prosper.