David Miliband is a complete and utter liar - US Threat.

This sounds like a very definite threat to me:

"Public disclosure of these documents... is likely to result in serious damage to US national security and could harm existing intelligence information-sharing arrangements between our two governments."

Miliband can be seen HERE denying that any threat was received from the US.

C4 have managed to get hold of three letters sent between the UK/US. Correspondence which "affirms in the clearest terms" the nature of the risk and threat to the Anglo American special relationship. You can download them HERE.