Is casting a spell considered a threatening action?

[Greenfield]

As far as a Fascinate trance is concerned, I think it was me who said that any spell breaks it, even if the target doesn't know it's being cast.

And according to the letter of RAW, that's how it works. RAI may be otherwise, but...

 

[kitcik]

RAI may well be otherwise in both cases, totally agree.

But if you take that statement as RAW, then casting a spell is an "obvious threat."

 

[Tharkon]

I don't know Charming Gaze but don't think that's relevant.

Casting any spell provokes an attack of opportunity, unless you're casting defensively (Concentration DC 10+spell level), not because it isn't threatening but because of the amount of concentration the casting requires making you unable to defend yourself.

Making a touch attack as part of a spell does not provoke an attack of opportunity since it's considered threatening enough to make the opponent concentrate on his defenses.