The government is proposing nuclear-powered drones to increase their loiter time, which suggests to me that the mice are learning to keep under cover to avoid getting a Hellfire missile in the trunk of their car.
Way back when, the government investigated nuclear cruise missiles. Very innovative, the missile consisted of a booster engine, a small but potent reactor, and a fuel tank which in this case was filled with ammonia.
The booster kicked the thing up into the air and far enough away from the launch point to protect the troops using it at which point the booster motor and all the reactor control rods were jettisoned. At this point the ammonia was pumped into the reactor, which controlled the internal temperature, and expelled out the back, hot enough to have become plasma. This made for a very efficient rocket engine.
To save weight, there was no reactor shielding and no warhead as such since the radiation from the unshielded reactor was sufficient to sterilize the ground in a swath about 1/4 mile wide beneath. It was expected to work best against soft targets such as infantry who would die slowly over the next week or so.
The drawback was that the newly created walking dead would have little or no compunction about suicide missions of the most desperate sort. Instant zombie apocalypse. As a final insult, I suppose the thing could be equipped with a modest conventional bomb under the reactor so that when the fuel ran out, presumably over a high-value target, the bomb would shower radioactive debris over the location rendering it uninhabitable for the next 1000 years or so.
As far as I know, this never got built, which is probably just as well.