| The longer answer is that leaking the document is being considered a breach of the Official Secrets Act and will be prosecuted accordingly. It would be a surprise to me to find out that Belgium has no similar laws protecting State secrets, I know the UK is not unique in having such laws.
The problem is that leaking Government documents is a way of life in Westminster. For instance there was a leak of a report into the Pension system only two days ago. The Government is happy to let these leaks slide when it suits them. Here though the contents of the leak are deeply embarassing to the US Government, an ally, but not to the UK Government. Neither can it be considered "damaging to national security". This leads us to wonder exactly why the Official Secrets Act is being waved around. If there were no truth in this matter then the story would have been vigorously denied and we'd have moved on already. | 
