Gates of Vienna has a linguistic analysis of Breivik’s manifesto, implying it was partially written by an American…..
The Breivik Portfolio, Part One: The American Connection
Also speculating that the CIA may be involved…

Some of the indications:

The unit had more people than usual.
They were focused on counter-terrorism.
There were other intelligence services involved.
They went to rallies and took photos.
They were pressuring Norway for lists of all terrorists, and Norway had not been cooperating.

Looking at it from one angle, this was normal behavior — the CIA was trying to do its job. But were they were also running some other type of operation?

If they weren’t, then shouldn’t the Norwegians ask them why they didn’t pick up on Anders Breivik? After all, he was a right-winger who communicated extensively in the English language. Shouldn’t the CIA’s surveillance have detected him?

These are the dots, but there is no clear connection among them — several coincidences, some fascinating possibilities, but no hard data. We are left with hypothesis and conjecture.