Nuclear warfare

• 1. Introduction

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  Nuclear warfare is the only form of combat in human history capable of ending civilization in an afternoon. On the 6th of August 1945, a single aircraft dropped a single bomb over Hiroshima, and within seconds roughly 70,000 people were dead. Three days later, a second bomb fell on Nagasaki. No nuclear weapon has been used in combat since. Yet today, thousands of warheads sit on missiles that can cross continents in under thirty minutes, and the clock that scientists use to measure how close we are to catastrophe stands at 85 seconds to midnight, the nearest it has ever been. How did the world arrive here? What happens when military strategists plan for wars that no one can survive? And what does survival even mean when the weapons in question can reshape the global climate for years?

• 2. Hiroshima and Nagasaki

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  Before the atomic bombs fell, the most destructive single night of bombing in aviation history was not nuclear at all. On the night of March 9 to 10, 1945, 279 Boeing B-29 Superfortress bombers dropped 1,665 tons of incendiaries on Tokyo in an operation called Meetinghouse. The fire they created generated winds of 50 meters per second, comparable to a tornado, killing an estimated 100,000 people and destroying 267,000 buildings in a single night. By early August 1945, an estimated 450,000 people had died as the U.S. firebombed a total of 67 Japanese cities.

  The alternative to the atomic bomb was a land invasion of Japan's home islands, codenamed Operation Downfall. American commanders estimated between 50,000 and 500,000 U.S. troops would die, with at least 600,000 to 1,000,000 others injured. President Harry S. Truman had the U.S. manufacture 500,000 Purple Hearts in anticipation. Over 400,000 American combatants had already died in both the European and Pacific theaters.

  On the 26th of July 1945, the United States, the United Kingdom, and the Republic of China issued the Potsdam Declaration demanding Japan's unconditional surrender, warning of "prompt and utter destruction" if it refused. Japan ignored the ultimatum. At that moment, only two atomic bombs existed, and the third would not be ready until September.

  The uranium bomb codenamed "Little Boy," with an energy of about 15 kilotons of TNT, destroyed nearly 50,000 buildings in Hiroshima and killed approximately 70,000 people, among them 20,000 Japanese combatants and 20,000 Korean slave laborers. The plutonium bomb codenamed "Fat Man," equivalent to about 20 kilotons of TNT, hit Nagasaki three days later, destroying 60 percent of the city and killing approximately 35,000 people, including 23,200 to 28,200 Japanese munitions workers and 2,000 Korean slave laborers. Industrial damage in Nagasaki was especially severe; 68 to 80 percent of non-dock industrial production was destroyed.

  Japan announced its surrender on the 15th of August 1945, signing the formal Instrument of Surrender on the 2nd of September 1945. The two bombings killed between 150,000 and 246,000 people in total, and their legacy shaped post-war Japan's Three Non-Nuclear Principles, which forbade the nation from developing nuclear armaments.

• 3. The Arms Race Takes Shape

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  J. Robert Oppenheimer, the Manhattan Project's lead manager, watched the Trinity test on the 16th of July 1945, the world's first nuclear detonation, and recalled a line from the Bhagavad Gita: "Now, I am become Death, the destroyer of worlds." The United States had hoped its monopoly on atomic weapons would offset the Soviet Union's superior conventional ground forces in Europe. That calculation collapsed on the 29th of August 1949, when the Soviet Union tested its first nuclear weapon at Semipalatinsk in Kazakhstan.

  American strategists had not expected the Soviets to develop nuclear capability so quickly. What they did not yet know was that the theoretical physicist Klaus Fuchs had conducted significant nuclear espionage from Los Alamos National Laboratory, and that the first Soviet bomb was a deliberate copy of the Fat Man plutonium device. In that same year, the U.S. drafted its first nuclear war plan against the Soviets, Operation Dropshot.

  The United Kingdom tested its first independent atomic bomb in 1952. France developed its first in 1960. China followed in 1964. A top-secret Royal Air Force white paper prepared for the British government in 1959 estimated that British V bombers alone could destroy key Soviet cities and military targets, killing an estimated 16 million people in the Soviet Union, half on impact and the rest fatally injured, before U.S. Strategic Air Command aircraft even reached their targets.

  The Doomsday Clock, maintained by the Bulletin of the Atomic Scientists since 1947, first reached its most alarming early setting in 1953, after both the U.S. and the Soviet Union began testing hydrogen bombs, pushing the clock to two minutes until midnight. The Soviet Union successfully tested the most powerful atomic bomb ever built, the Tsar Bomba, on the 30th of October 1961. It yielded 50 megatons, the equivalent of 50 million tons of conventional explosives.

• 4. Doctrine, Deterrence, and MAD

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  Soviet military doctrine did not match American doctrine in a crucial way. American strategists assumed the Soviets shared their belief in mutually assured destruction, the logic that neither side would strike first because the retaliation would be unsurvivable. Soviet planners, by contrast, assumed they could fight and win a nuclear war, expecting a large-scale exchange followed by a conventional war involving heavy use of tactical nuclear weapons. To test this doctrine, Marshal Georgy Zhukov commanded an exercise on the 14th of September 1954, north of Totskoye village in Orenburg Oblast, Russia, codenamed "Snowball." A nuclear bomb roughly twice as powerful as the one dropped on Nagasaki was detonated, and an army of approximately 45,000 soldiers then maneuvered through the hypocenter immediately after the blast.

  Henry Kissinger, in his controversial 1957 book Nuclear Weapons and Foreign Policy, argued that any nuclear weapon below 500 kilotons in yield, detonated in air burst mode to avoid serious fallout, could be more decisive and less costly in human lives than a protracted conventional war. Some Cold War strategists called limited nuclear war "global nuclear holocaust in slow motion," arguing that once any nuclear exchange occurred, others would follow over decades, rendering the planet uninhabitable through a slower path to the same result.

  The introduction of the intercontinental ballistic missile, which the Soviet Union successfully tested in August 1957, transformed the strategic balance. A missile was faster and more cost-effective than a bomber, and ICBMs were extremely difficult to intercept given their high altitude and speed. Early ICBMs and bombers were relatively inaccurate, which pushed strategists toward countervalue strikes, attacks directly on enemy populations intended to collapse the will to fight.

  By the late 1960s, both the U.S. and the Soviet Union possessed enough warheads to completely destroy each other's infrastructure and kill a large proportion of each other's population. A balance of terror called mutually assured destruction took hold. Neither side could risk initiating a direct confrontation, and both were driven instead toward lower-intensity proxy wars around the globe.

  In 1996, the United States adopted a policy of allowing the targeting of nuclear weapons at non-state actors armed with weapons of mass destruction, a significant expansion of nuclear doctrine beyond state-versus-state conflict.

• 5. Close Calls and False Alarms

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  The Cuban Missile Crisis of 1962 is often considered the closest the world has come to a nuclear exchange. The Soviet Union placed medium-range ballistic missiles 90 miles from the United States, possibly as a direct response to American Jupiter missiles placed in Turkey. After intense negotiations, the Soviets removed the missiles from Cuba. The U.S. dismantled its launch sites in Turkey in exchange, though this was done secretly and not publicly revealed for over two decades. First Secretary Nikita Khrushchev did not even reveal this part of the agreement when he came under fire by political opponents. The communication failures during the crisis led directly to the establishment of the Moscow-Washington hotline.

  Israel's nuclear activity during the 1973 Yom Kippur War illustrated how quickly a regional conflict could approach nuclear thresholds. When Syrian tanks swept across the Golan Heights, Israel assembled 13 nuclear weapons in a tunnel under the Negev desert. On the 8th of October 1973, Israeli Prime Minister Golda Meir authorized Defense Minister Moshe Dayan to activate those 13 warheads and distribute them to air force units for possible use if Israel began to be overrun. On October 24, as U.S. President Richard Nixon was preoccupied with the Watergate scandal, Henry Kissinger ordered a DEFCON-3 alert preparing American B-52 nuclear bombers for war, after intelligence indicated the USSR was preparing to defend Egypt.

  Early warning systems produced dangerous false alarms with troubling frequency. On 78 occasions in 1979 alone, a "missile display conference" was called to evaluate detections described as "potentially threatening to the North American continent." On the 26th of September 1983, Soviet officer Stanislav Petrov received convincing indications of an American first strike launch but correctly assessed the warning as a false alarm, and did not report upward. Soviet policy at the time called for an immediate nuclear response upon detecting inbound ballistic missiles. In November 1983, the Soviet Union came unusually close to launching a nuclear strike when it mistook the NATO military exercise Able Archer 83 for a cover to begin a nuclear first strike, raising readiness and preparing its arsenal for immediate use. The crisis passed only when the exercise concluded without incident.

  In 1995, a Black Brant sounding rocket launched from Norway's Andoya Space Center triggered a high alert in Russia, with the Russians initially believing it might be a nuclear missile launched from an American submarine.

• 6. Proliferation and Modern Risk

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  India conducted its first nuclear test on the 18th of May 1974, at the Pokhran test range, in an operation named Smiling Buddha, which India described as a "peaceful nuclear explosion." Pakistan's nuclear program, driven substantially by the history of conflict with India, including the 1965 and 1971 wars, eventually culminated in tests at Chagai. By 1998, both countries had publicly demonstrated nuclear capability. Recent CIA studies have cited the India-Pakistan conflict as the single "flash point" most likely to escalate into a nuclear war. During the 1999 Kargil War, Pakistan came close to using nuclear weapons as conventional military fortunes deteriorated. Pakistan's foreign minister warned that the country would "use any weapon in our arsenal."

  North Korea conducted an underground nuclear test on the 9th of October 2006, confirmed by a 4.2-magnitude earthquake measured by the U.S. Geological Survey. South Africa stands as the only country that ever manufactured a complete nuclear arsenal and then voluntarily eliminated it, doing so during the 1990s after having developed the capability during the 1970s and early 1980s.

  A 2022 peer-reviewed study published in Nature Food calculated that a full-scale nuclear war between the U.S. and Russia would kill 360 million people directly, with a further 5 billion people dying from starvation. A smaller-scale war between India and Pakistan would kill more than 2 billion people. A separate study presented at the American Geophysical Union's December 2006 annual meeting found that a limited regional nuclear conflict using 50 Hiroshima-sized weapons per country could release as much as five million tons of soot, producing a cooling of several degrees over large areas of North America and Eurasia, lasting years and potentially catastrophic to grain-growing regions.

  On the 24th of February 2022, preceding the start of the Russo-Ukrainian war, Russian President Vladimir Putin stated that Russia "is today one of the most powerful nuclear powers in the world" and warned that interference would lead to "consequences that you have never experienced in your history." The threat of nuclear war is considered to have resurged substantially since that date. In March 2026, U.S. Director of National Intelligence Tulsi Gabbard noted that Russia and China possess systems "capable of penetrating or bypassing U.S. missile defenses," while North Korea's missiles can already reach U.S. soil.

• 7. Survival and Civil Defense

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  FEMA's Cold War-era survival estimate CRP-2B predicted that 80 percent of Americans would survive a nuclear exchange with the Soviet Union, a figure criticized by the Federation of American Scientists for ignoring the collapse of healthcare infrastructure, the food supply, and the ecosystem, and for assuming all major cities could be evacuated within three to five days. More pessimistic assessments from the same era held that a full-scale nuclear war could bring about human extinction, or near extinction, leaving only a small number of survivors in remote areas with a reduced quality of life for centuries afterward.

  During the Cold War, the U.S. established CONELRAD radio information systems that would broadcast on two AM frequencies, 640 and 1240 kHz, in civil defense emergencies. These frequencies were marked with small triangles on radio dials of the period. Schools stocked basements with non-perishable food, canned water, first aid supplies, and dosimeter and Geiger counter radiation-measuring devices. The British government developed a public alert system with the expectation of a four-minute warning before detonation; the United States expected warnings ranging from half an hour for land-based missiles to under three minutes for submarine-based weapons.

  Switzerland's shelter program went further than most. The majority of Swiss homes have an underground blast and fallout shelter, and the country has overcapacity, able to accommodate slightly more than the entire national population. Pyongyang's metro stations were constructed 110 meters below ground and designed to serve as nuclear shelters, each entrance fitted with thick steel blast doors.

  The pharmaceutical stockpile the U.S. maintains for nuclear emergencies includes Prussian blue (sold as Radiogardase), potassium iodide, and DTPA, all useful in treating internal exposure to harmful radioisotopes in fallout. Recent scientific research has explored partial body shielding as a survival strategy, targeting the pelvic region specifically because it holds 50 percent of the body's bone marrow supply and is close to other radio-sensitive abdominal organs. The logic is that protecting enough bone marrow to repopulate damaged areas using hematopoietic stem cells could defer the onset of acute radiation syndrome, the most immediate threat from high-dose gamma radiation exposure.