The CBU-24, MK 20 Rockeye, and Napalm-B all dominated the battlefields of the Vietnam War—likely saving American lives in combat, but creating misery for Vietnamese civilians and fueling anti-war protests.
America’s war in Vietnam was ultimately a tragic affair for all parties involved. Mismanaged and poorly strategized, the war lasted ten grueling years, triggered massive domestic upheaval in the United States, hurt the American economy, and resulted in the US military’s first strategic defeat. This is to say nothing of the misery it inflicted on the people of Southeast Asia; according to the Pentagon’s own assessments, the United States dropped more bombs on Vietnam, Cambodia, and Laos throughout the war than it did in the entirety of World War II.
It was during the Vietnam War that America’s cult of airpower reached its zenith—yet failed to achieve the victory that America’s politicians had been promising the American people. Among the three most commonly used bombs by US air forces in the war, the CBU-24 cluster bomb, Mk 20 Rockeye anti-tank cluster bomb, and the Napalm-B incendiary bomb stand out. Dropped from aircraft like the iconic F-4 Phantom and B-52 Stratofortress, these weapons aimed to disrupt the North Vietnamese Army (NVA) and Viet Cong (VC) guerrilla operations. The effectiveness of the three bomb types stemmed from their wide-area coverage—a key element in dealing with a dispersed, guerrilla force, of the kind that the NVA-VC represented—but they also raised enormous ethical concerns due to civilian casualties and long-term environmental impacts.
The CBU-24 Cluster Bomb Fueled Decades of Misery in Vietnam
The CBU-24, a key cluster bomb during the Vietnam War era, was an unguided dispenser releasing up to 665 BLU-24/B bomblets—small, roughly baseball-sized explosives filled with steel fragments. Developed for anti-personnel and anti-material roles, this weapon was used extensively in air strikes against troop concentrations, supply lines, and hidden positions in Cambodia, Laos, and Vietnam from 1964 through 1973.
A CBU-24 bomb opened at a preset altitude, scattering its bomblets over areas of up to 120 by 200 feet, creating a deadly footprint of fire, repulsive concussions, and spraying molten hot steel at enemy formations. If there was a more brutal way to go, it might have been by the Napalm-B bombs (we’ll get to that one shortly) but there are few other more horrific ways to be killed.
Analysis conducted of the effectiveness of the CBU-24 indicated that this type of cluster munition produced eight times more casualties than standard high-explosive bombs, excelling against dispersed, dug-in forces. In operations like the Ho Chi Minh Trail bombings, CBU-24s disrupted key NVA logistics by saturating trails with unexploded ordnance (UXO), which deterred movement long after strikes.
Unfortunately, the CBU-24 came with what is known as a “high dud rate”—meaning that in any given dispersal, up to 30 percent of the bomblets failed to go off. This did not, however, mean that the explosives were inert; they could be accidentally triggered months after a battle ended by a civilian, causing thousands of postwar deaths and complicating clearance efforts.
The Mk 20 Rockeye Devastated North Vietnamese Armor
The Mk 20 Rockeye was an anti-armor cluster bomb carrying 247 Mk 118 shaped-charge bomblets designed to penetrate tanks and vehicles. First deployed in Vietnam in the late 1960s, it targeted NVA armored convoys and fortified positions, covering up to 3,300 square yards upon release. Unlike general-purpose cluster bombs, its bomblets used explosive jets to pierce armor, making it ideal for halting mechanized threats in rugged terrain.
The Rockeye’s effectiveness shone in scenarios like the 1972 Easter Offensive, in which the NVA attempted to openly conquer South Vietnam in a conventional invasion. As America and South Vietnam worked to repel the invasion, they learned that multiple Rockeye bomblets could disable a tank through cumulative hits, even if each one was not catastrophic individually. It outperformed conventional bombs against mobile targets, with reports of high kill rates on trucks and light armor. However, like the CBU-24, UXO issues persisted, contributing to long-term hazards. Its design influenced later variants, such as the CBU-99 and CBU-100, emphasizing anti-tank roles in US arsenals.
Napalm Became a Symbol of the Vietnam War
Napalm-B, an upgraded mixture of gasoline with polystyrene for better adhesion and burn duration, could create flames up to 2,500 square yards per bomb. Used prolifically—with over 388,000 tons dropped across Vietnam—the weapon defoliated jungles, destroyed crops, and flushed out entrenched VC elements from bunkers and tunnels. Its psychological impact was profound, breaking enemy morale through terror and oxygen deprivation in confined spaces.
In combat, Napalm-B proved highly effective against fortified positions, where high-explosives faltered; it incinerated cover and inflicted horrific burns, reducing American casualties in close-quarters fights.
Operations like Arc Light showcased napalm’s utility in supporting ground troops, but its overuse led to environmental devastation across Vietnam. It also became emblematic of the war’s impact on Vietnamese civilians, and the visual horror it produced fueled anti-war protests in the United States.
Though napalm has not been banned for military use, the controversy surrounding its use shifted US military doctrine toward precision alternatives in the conflicts that followed Vietnam.
The Vietnam War’s Lasting Influence on American Bomb Designs
These Vietnam-era bombs profoundly influenced modern American munitions. The CBU-24’s success spurred evolutions like the CBU-87 Combined Effects Munition, which improved reliability and reduced duds through better fuzing. Similarly, the Mk 20 Rockeye paved the way for advanced anti-armor clusters, used to great effect against Iraqi tanks during the Gulf War—and leading to recent Ukrainian adaptations for drone munitions.
Likewise, the backlash against the use of napalm prompted a doctrinal pivot to fuel-air explosives and thermobaric weapons, minimizing incendiary use while retaining area effects.
Humanitarian concerns from Vietnam led to the 2008 Convention on Cluster Munitions, although the United States has not ratified that agreement, opting instead for “smart” submunitions with self-destruct features. Overall, these weapons accelerated the shift toward precision-guided bombs, balancing lethality with reduced collateral damage.
The CBU-24, MK 20 Rockeye, and Napalm-B all dominated the battlefields of Vietnam. They caused great carnage. They may have saved countless American lives during combat with NVA and VC forces, too. But despite their ubiquity and lethality, these weapons did not ultimately turn the tide of the war in America’s favor. They were tactically brilliant weapons, but strategically held little to no value when all was said and done in Vietnam.
About the Author: Brandon J. Weichert
Brandon J. Weichert is a senior national security editor at The National Interest. Recently, Weichert became the host of The National Security Hour on America Outloud News and iHeartRadio, where he discusses national security policy every Wednesday at 8pm Eastern. He is also a contributor at Popular Mechanics and has consulted regularly with various government institutions and private organizations on geopolitical issues. Weichert’s writings have appeared in multiple publications, including The Washington Times, National Review, The American Spectator, MSN, The Asia Times, and others. His books include Winning Space: How America Remains a Superpower, Biohacked: China’s Race to Control Life, and The Shadow War: Iran’s Quest for Supremacy. His newest book, A Disaster of Our Own Making: How the West Lost Ukraine is available for purchase wherever books are sold. He can be followed via Twitter @WeTheBrandon.
Image: Wikimedia Commons.
