[The World Through Weapons] Low-Yield vs. High-Yield Nuclear Warheads: Which Is More Dangerous?

A submarine-launched ballistic missile (SLBM) fired from a US military submarine. [Image source=US Navy website/www.navy.mil]

[Asia Economy Reporter Hyunwoo Lee] Recently, the U.S. Department of Defense announced for the first time that it has deployed submarine-launched ballistic missiles equipped with low-yield nuclear warheads in actual combat, drawing worldwide attention. Low-yield nuclear warheads refer to nuclear weapons that have less explosive power than strategic nuclear weapons and emit very low levels of radioactive contamination. However, because the damage is less severe, these nuclear weapons are much more likely to be used on the battlefield as conventional forces. Although the weapon's power is reduced, the increased likelihood of actual use ironically makes them more dangerous in reality.

On the 4th (local time), the U.S. Department of Defense stated that the U.S. Navy has deployed the W76-2 missile, a submarine-launched ballistic missile (SLBM) equipped with a low-yield nuclear warhead, in actual combat on submarines. The Department of Defense emphasized that this deployment will help strengthen deterrence against potential adversaries such as Russia. Previously, the Federation of American Scientists (FAS) revealed that the U.S. Navy had equipped the low-yield nuclear weapon on the USS Tennessee, a U.S. nuclear submarine, and deployed it in the Atlantic Ocean, but this is the first time the U.S. Department of Defense has officially announced it through a statement. With this, the U.S. military has become the first in history to deploy low-yield nuclear warheads on submarines in actual combat.

Missile launcher of a US nuclear submarine Photo by AP Yonhap News

Here, low-yield nuclear warheads refer to nuclear weapons with less power than strategic nuclear weapons. They have an explosive power of about 5 kilotons (kt), which is about 1/100th of a typical SLBM nuclear warhead. The radioactive contamination level is also known to be about 10% compared to strategic nuclear weapons. At first glance, it seems that the weapon's power has been reduced, but this is not the case. Low-yield nuclear warheads have a higher likelihood of being used in actual combat compared to strategic nuclear weapons. Even though their power is weaker than strategic nuclear weapons, they can devastate an area within a 2 km blast radius, making them extremely powerful weapons compared to conventional arms.

In fact, since the Cold War era of the 1950s, nuclear weapons generally referred to strategic nuclear weapons, which were capable of destroying an entire large city in one strike. However, because of their immense power, they have rarely been used in actual combat. The weapons were so powerful that they became more difficult to use. This is commonly referred to as the "mutually assured destruction" strategy. Since using such weapons first would lead to retaliation with similar weapons, resulting in mutual destruction, both sides have strived to avoid using them in actual combat.

Paradoxically, analyses suggest that the reason why there was no large-scale firepower battle during the Cold War, unlike in World Wars I and II, was due to these nuclear weapons. This was called the "Balance of terror." Nuclear weapons were only used in actual combat at the end of the Pacific War when the U.S. dropped atomic bombs on Hiroshima and Nagasaki. Since then, although nuclear weapons have advanced significantly, they have never been used again. This was largely due to the fear that once used, the situation could spiral out of control.

Ballistic missile test launch footage released by the U.S. military immediately after withdrawing from the Intermediate-Range Nuclear Forces Treaty (INF) in August last year [Image source: U.S. Department of Defense website/www.defense.gov]

However, tactical nuclear weapons like low-yield nuclear warheads are different. They have greater explosive power than bunker busters designed to destroy underground military facilities, and their radioactive contamination levels are low enough that ground troops can be deployed within hours after detonation. Therefore, they could be used more actively in ground warfare. They can be easily deployed not only on submarines but also on bombers, increasing the likelihood of their use in conventional battles. In regions like the Middle East and Africa, where local conflicts continue, the deployment of conventional weapons with higher lethality is becoming common, raising concerns.

Since withdrawing from the Intermediate-Range Nuclear Forces Treaty (INF) in August last year, the U.S. has been accelerating the strengthening of tactical nuclear and missile forces. This is due to the intensifying nuclear arms race with Russia. As Russia showcases new nuclear capabilities such as hypersonic cruise missiles, support for low-yield nuclear weapons is spreading within the U.S. Although the possibility of direct confrontation between the two countries remains low, since both sides are engaged in proxy wars in global civil war zones, concerns are growing that low-yield nuclear warheads may soon be used in these battlefields.