The threat of the use of nuclear weapons by the aggressor is a significant factor in the ongoing war. Also in future, the Ukrainian government (any leadership) will be interested in its own nuclear weapons at least as long as Russia is ruled by an ill-predictable authoritarian regime. Nuclear arms could be helpful for Ukraine both for deterrence and to increase the attractiveness of the country as a military ally. However, due to many economic, political, and legal factors discussed in the paper, the likelihood of development of Ukraine’s own nuclear arsenal should be considered as extremely low. The unlikely scenario, in which Ukraine could nevertheless develop such weapons, would require such a significant improvement of political and economic institutions, that the risk for third countries from the new nuclear actor will remain minimal.