Assuming rationality or optimal play is not good way to think of real world actions. You only need three things for something like this to happen.

1. One side thinks[1] that it will hurt the other side more than it does to itself.

2. Politically it can handle/sell the cost of such an action.

3. There is a leader who is ready to execute it as his agenda.

[1] Only have to think so, it doesn't have to even be true.