They have a right to do whatever they want. However, that doesn't mean they should.
It's a real quandary we face in this new century. The technology is out there, it's available to any country with the money and infrastructure to use and the only way to stop a potential war with nukes is to preemptively go to war to stop them. Obviously THAT isn't a sustainable track. So weapons and delivery systems proliferate and eventually the lowest common denominator will be able to decide when and where in the world to begin a nuclear war. In the lead up to the 1967 war the Russians and US were talking about how to avoid the powers being drawn precipitously into a war in the M.E. I hope something similar is happening these days for a more general threat that could materialize over night. If nukes get used anywhere I hope it can be contained.
Hanlon's Razor: "Never attribute to malice that which can be adequately explained by stupidity."