Ukraine Gave up Thousands of Nuclear Warheads

Super fact 47 : In 1991, after the dissolution of the Soviet Union, Ukraine became the third largest nuclear power in the world after Russia and the United States. Ukraine held about one third of the former Soviet nuclear weapons and delivery systems. Ukraine agreed to transfer these weapons to Russia for dismantlement in exchange for economic compensation and assurances to respect Ukrainian independence and borders.

After the dissolution of the Soviet Union in 1991, Ukraine inherited an estimated 1,700 to 1,900 strategic nuclear warheads, 130 UR-100N intercontinental ballistic missiles (ICBM) with six warheads each, 46 RT-23 Molodets ICBMs with ten warheads apiece, and an estimated 2,650-4,200 tactical nuclear weapons. It should be noted that these nuclear warheads were not under Ukrainian control.

In 1994, Ukraine agreed to transfer these weapons to Russia for dismantlement in exchange for economic compensation and assurances from Russia, the United States and the United Kingdom to respect Ukrainian independence and sovereignty within its existing borders. These political agreements are referred to as the Budapest Memorandum.

These events are relevant to what is happening in Ukraine today, and yet it is seldom discussed, and many people are unaware of or have forgotten about this history. It also comes as a surprise to many that there are nuclear states who have relinquished their nuclear weapons. This is why I call this fact a super fact.

Nine Nuclear States

There are nine nuclear states in the world as of 2025 according to the Federation of Atomic Scientists. There are 12,331 nuclear warheads including 9,600 in active military stockpiles.

• Russia – 5,449 warheads
• The United States – 5,277 warheads
• China – 600 warheads
• France – 290 warheads
• United Kingdom – 225 warheads
• India – 180 warheads
• Pakistan – 170 warheads
• Israel – 90 warheads
• North Korea – 50 warheads

There are also countries that are hosting nuclear warheads owned by other countries.

• Italy (the United States) – 35 warheads
• Turkey (the United States) – 20 warheads
• Belgium (the United States) – 15 warheads
• Germany (the United States) – 15 warheads
• Netherlands (the United States) – 15 warheads
• Belarus (Russia) – ? warheads

Four nations that relinquished their nuclear weapons programs

The four nations that relinquished their nuclear weapons programs are Belarus, Kazakhstan, South Africa, and Ukraine. Belarus, Kazakhstan, and Ukraine returned their inherited nuclear weapons to Russia after the dissolution of the Soviet Union. However, it should be noted that in 2023 Russia began deploying tactical nuclear weapons to Belarus. However, Belarus does not currently possess its own nuclear weapons. South Africa voluntarily dismantled its nuclear weapons program in 1991.

How to Build a Nuclear Bomb

This section is just some extra reading that is only somewhat related to the topic. However, since it is an interesting topic somewhat related to the topic I might as well explain how to build a nuclear bomb. Don’t worry I will not present any engineering details, only general principals, which is all I know, and which are already all over internet. Besides if I were to give detailed engineering instructions some peacenik hippie might have a hissing fit and swear in the comment section (that was a joke).

Anyway, the main idea behind a nuclear fission bomb is to achieve a runaway chain reaction. A fusion bomb, or a so-called hydrogen bomb is different. To create a fission bomb you are not looking for the most radioactive materials there are. You are looking for a fuel which you can use to create a runaway chain reaction, and which is also stable enough to make a bomb possible, in other words not too radioactive. Basically, the fuel must be just right. The primary fuels used in fission bombs are uranium-235 and plutonium-239. These isotopes undergo fission when struck by neutrons, releasing a massive amount of energy in a chain reaction.

I should explain, isotopes are different forms of an element. For example, hydrogen comes in three different forms, a nucleus with just a proton, a nucleus with one proton and one neutron (deuterium), and a nucleus with one proton and two neutrons (tritium). Isotopes for the same element are chemically identical but have different atomic weight and they may or may not be radioactive.

The three isotopes of Uranium are uranium-234, uranium-235, and uranium-238. The one we need is uranium-235, which has 92 protons and 143 neutrons in the nucleus. The isotopes of Plutonium include Pu-238, Pu-239, Pu-240, Pu-241, and Pu-242 but there are others. The one we need is plutonium-239, which has 94 protons and 145 neutrons in the nucleus. There are more than 3,500 known isotopes of which 3,000 are radioactive.

During Uranium-235 fission, an average of 2.5 neutrons are released. Specifically, the fission of U-235 typically releases 2 or 3 neutrons, with the average being close to 2.5. During the fission of plutonium-239, an average of 2.9 neutrons are released (depending on the energy of the incident neutron). The important thing for bomb making is that one atom/nucleus releases enough neutrons so that the neutrons from one nucleus cause more than one fission. For example, a nucleus releases three neutrons and two of those neutrons cause two more fission events, which in turn cause four fission events, etc. 2, 4, 8, 16, 32, 64, a trillion…

By putting together enough U-235 you can make it so that one fission event will result in more than one additional fission event. This is called the critical mass. The critical mass for U-235 is 47 kilograms (104 pounds). Theoretically, you can achieve this by taking a 24-kilogram half sphere of U-235 in your right hand and a 24-kilogram half sphere of U-235 in your left hand and bring them together. You will achieve a limited chain reaction for a nano second, but you will just blow the two halves apart and kill yourself, but your city will survive. This is called a fizzle. To make most of the 48-kilogram mass undergo fission you have to force them together long enough for the chain reaction to complete (or almost complete). This requires force and precise calculations. See the illustration below.

Another difficulty is obtaining nearly 100% U-235 from natural uranium. 99% of the Uranium you find in nature is U-238. U-235 and U-238 chemically identical so extracting U-235 from natural uranium is difficult. However, U-235 is slightly lighter than U-238 so you can use centrifugal separation as you do to separate cream from milk. What is typically done is using a uranium compound, uranium hexafluoride, heat it into gaseous form and then utilize centrifugal separation to extract the uranium hexafluoride with U-235 isotopes. After that you can chemically extract the uranium, which is now U-235.

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