Plant a few in Pakistan and set them off if it escalates. No one will think we did it.
The possibility of a 3rd party medaling in this would seem high. If either side were to learn that the other was preparing a first strike, and learn it in a way that convinces them it was true, an immediate first strike would be the only option. Planted intelligence could thus predictably cause a nuclear war, so the question is who gain from that and how.