Ideally, your decision to follow that precommitment should be so strong that you don't really have a choice, retaliating is something you don't even think about but execute by default. With precommitments, you want to restrict your own decision-possibilities.

If I hadn't dissolved the question already, I'd probably have come up with something like "by making precommitments, you want to undermine your free will so that once that events (nuclear strike etc.) happened, you don't have a free choice anymore because your free will is nonexistent in that situation".