Re: Is aiki a clash of forces?
To have a stab...
Aiki is a unification of center; a grafting of a dominated center onto a dominating center. I am not sure I would use the term "clash" because that implies there is a period of oppositional struggle. There is not. I believe Takeda sensei used to refer to this unification as defeating your opponent in an instant [by glancing at him]. I also believe Ueshiba sensei used a similar reference.
Atari is the point at which centers meet, a confrontation. I like this term better because it leaves out an implied action to follow. This is an older term and I think Endo sensei uses it well; to be fair, several of his students use it also with clarity too, Gleason sensei comes to mind (I think he talks about this topic in one of his books).
So yes, for me aiki has confrontation. Of confronted centers, one will become dominant and others will be dominated. For me, this is what I call kihon - the root of anything we will do in aikido must first begin by unifying and dominating my partner's center. The trick to it is making your center dominate without resorting to "doing" something to your partner.