We've had some alien species try to invade for a really long time, but there wasn't really communication from them. Hard to say if they had any affiliation...

[But they sure did fight tooth and nail over the planet for no apparent reason for such an incredibly long time it had been doubtful the war would ever end.

9S shrugs, at a loss for relevant data, and yet he knows that really is a very good question]

So far as I know, it was the aliens' machines fighting us androids.