Here's a start then you can go from there. I highly suggest studying and learning about war and the history of it.
Strategic Disadvantages: Tactically, nuclear weapons are not well-suited for the current conflict. Ukraine is a neighboring country with a shared border, and fallout from a nuclear strike could harm Russian territory, citizens, or occupied regions Russia claims as its own (e.g., parts of eastern Ukraine). Environmental and geopolitical backlash would also be severe, potentially alienating allies like China and India, who have urged restraint.

International Isolation: Using nuclear weapons would likely lead to unprecedented global condemnation and economic consequences, further isolating Russia. Even countries that have remained neutral or supportive, such as China, have signaled opposition to nuclear escalation. Posts on X and some analyses suggest Russia values its conventional military capabilities and would prefer to rely on them rather than risk total diplomatic and economic ruin.

Deterrence vs. Action: Russia’s nuclear rhetoric appears designed to deter NATO involvement and Ukraine’s Western backers rather than signal an intent to act. Historical patterns show Moscow issuing threats—e.g., in 2022 and 2024—without following through, as noted in some X posts and news reports. Ukraine’s intelligence chief, Kyrylo Budanov, stated in 2023 that Russia’s leadership isn’t run by “idiots” and wouldn’t risk nuclear use lightly.