Ukraine could technically restore nuclear status in just four years, experts say

This was stated by nuclear weapons and disarmament expert Pavlo Podvyh in an interview with Radio Svoboda.

"If there are no political restrictions, if Ukraine is not being bombed, then it can be done at a rapid pace in about four years. Take the Manhattan Project or the Soviet nuclear weapons program as an example. The USSR had some minor developments before, but the actual active work on the program began in 1949. And there you have four years. Of course, this was happening under conditions where there were no other obstacles, including political ones, and no opposition from your neighbor, but overall, four years is a realistic timeline for Ukraine," Podvyh believes.

In addition, according to him, since international bans apply only to materials, not the mechanisms needed for a nuclear bomb to function (such as detonators that initiate the chain reaction and reflectors that prevent neutrons from "escaping" the charge during fission), "Ukraine can create the latter almost 'painlessly,' in terms of the international community's response."

Two paths: uranium and plutonium

A nuclear bomb can be created in two different ways: using uranium or plutonium, according to Radio Svoboda.

To create nuclear weapons, the uranium isotope U-235 is needed, and it makes up only 0.7% of natural uranium, with the rest (over 99%) being the unusable U-238 isotope. To convert regular uranium into weapon-grade material, it must be enriched, meaning the U-235 content is increased to about 90%, as it is capable of sustaining the chain reaction necessary for an explosion.

"Enrichment is mainly carried out using centrifuges: uranium is converted into a gaseous state and often passed through these centrifuges. Due to centrifugal force, heavier molecules with uranium-238 shift to the wall, while lighter molecules with uranium-235 move closer to the center. This process is repeated many times in large numbers of centrifuge systems (also called 'cascades'), because the isotope ratio in uranium barely changes after one enrichment cycle: this requires huge power and many repetitions," according to an article published on April 20, 2025.

The "plutonium route," however, as Podvyh points out, is simpler than the "uranium route" because it is technologically easier to build a reactor and radiochemical production than to set up all the necessary systems for uranium-based nuclear weapons.

Additionally, plutonium has a significant advantage with its critical mass: 10 kilograms versus 50 kilograms for uranium, and it is easier to extract 10 kilograms of plutonium than 50 kilograms of weapon-grade uranium.