I'd like to echo Tim's comments about aikido being very proactive.
Passively sitting and waiting to be attacked is something we train in for the first couple of years of learning aikido, but after that we should really be moving to a more proactive approach. Look at O'sensei's original training manual: In the explanations the first step always comes from Tori (admittedly, that first step is sometimes "Tori fills their body with ki and invites uke to attack" - but its not passive, and fewer than half the techniques listed there).
The one time I've had to use aikido, I was in the middle between two people who were getting progressively angrier with one another -- a younger man and an older man. I'm not going to go into details, but I'm related to both and was trying to calm things down. As things got worse, I remember thinking that if the younger guy moves, I'm going to take him down. He moved, and I took him down.
In a sense, you could say that I attacked him with aikido -- he actually moved away from me. I did a beautiful kyzushi that lead into a great pin that immediately calmed things down and left my no-longer-quite-as-angry young friend unhurt. I, on the other hand, tenkaned right into the back of a wooden chair and had a very nasty bruise for the next week or so.
The point is, I didn't wait for him to move before deciding to take action. I decided to take action and then he moved.
To flip things around, could he have done anything after I attacked him? Probably. It would have been difficult while I was throwing him, but if he had wanted to continue to struggle after I took him to the floor, it could have gotten nasty. I was lucky that he calmed down right away.