If this were true, there would already be nuclear powered aircraft which would be a much more "achievable" goal given the size and weight of even the smallest nuclear power plants.
But there are no nuclear powered aircraft and so no nuclear powered missiles. And many countries have had nuclear _capable_ weaponry for a very long time because nuclear weapons can be small and relatively light.
The cruise missile is technically easier than the airplane because you don't need to shield the pilot or crew, which is the really hard part in the air because radiation shielding is heavy.
But there are no nuclear powered aircraft and so no nuclear powered missiles. And many countries have had nuclear _capable_ weaponry for a very long time because nuclear weapons can be small and relatively light.
So there is no news except for the very gullible.