Weapon of mass destruction in the context of "Nuclear war"

Human extinction or omnicide is the end of the human species, either by population decline due to extraneous natural causes, such as an asteroid impact or large-scale volcanism, or via anthropogenic destruction (self-extinction).

Some of the many possible contributors to anthropogenic hazards are climate change, global nuclear annihilation, biological warfare, weapons of mass destruction, and ecological collapse. Other scenarios center on emerging technologies, such as advanced artificial intelligence, biotechnology, or self-replicating nanobots.

The use of toxic chemicals as weapons dates back thousands of years, but the first large-scale use of chemical weapons was during World War I. They were primarily used to demoralize, injure, and kill entrenched defenders, against whom the indiscriminate and generally very slow-moving or static nature of gas clouds would be most effective. The types of weapons employed ranged from disabling chemicals, such as tear gas, to lethal agents like phosgene, chlorine, and mustard gas. These chemical weapons caused medical problems. This chemical warfare was a major component of the first global war and first total war of the 20th century. Gas attack left a strong psychological impact, and estimates go up to about 90,000 fatalities and a total of about 1.3 million casualties. However, this would amount to only 3–3.5% of overall casualties, and gas was unlike most other weapons of the period because it was possible to develop countermeasures, such as gas masks. In the later stages of the war, as the use of gas increased, its overall effectiveness diminished. The widespread use of these agents of chemical warfare, and wartime advances in the composition of high explosives, gave rise to an occasionally expressed view of World War I as "the chemist's war" and also the era where weapons of mass destruction were created.

The use of poison gas by all major belligerents throughout World War I constituted war crimes as its use violated the 1899 Hague Declaration Concerning Asphyxiating Gases and the 1907 Hague Convention on Land Warfare, which prohibited the use of "poison or poisoned weapons" in warfare. Chemical weapons in World War II saw widespread use by Germany during the Holocaust and by Japan against China. Battlefield use against Western Allies was prevented by deterrence.

Nuclear warfare, also known as atomic warfare, is a military conflict or prepared political strategy that deploys nuclear weaponry. Nuclear weapons are weapons of mass destruction; in contrast to conventional warfare, nuclear warfare can produce destruction in a much shorter time and can have a long-lasting radiological result. A major nuclear exchange would likely have long-term effects, primarily from the fallout released, and could also lead to secondary effects, such as "nuclear winter", nuclear famine, and societal collapse. A global thermonuclear war with Cold War-era stockpiles, or even with the current smaller stockpiles, may lead to various scenarios including human extinction.

To date, the only use of nuclear weapons in armed conflict occurred in 1945 with the American atomic bombings of Hiroshima and Nagasaki. On August 6, 1945, a uranium gun-type device (code name "Little Boy") was detonated over the Japanese city of Hiroshima. Three days later, on August 9, a plutonium implosion-type device (code name "Fat Man") was detonated over the Japanese city of Nagasaki. Together, these two bombings resulted in the deaths of approximately 200,000 people and contributed to the surrender of Japan, which occurred before any further nuclear weapons could be deployed.

The United States Department of Homeland Security (DHS) is the U.S. federal executive department responsible for public security, roughly comparable to the interior, home, or public security ministries in other countries. Its missions involve anti-terrorism, civil defense, immigration and customs, border control, cybersecurity, transportation security, maritime security and sea rescue, and the mitigation of weapons of mass destruction.

It began operations on March 1, 2003, after being formed as a result of the Homeland Security Act of 2002, enacted in response to the September 11 attacks. With more than 240,000 employees, DHS is the third-largest Cabinet department, after the departments of Defense and Veterans Affairs. Homeland security policy is coordinated at the White House by the Homeland Security Council. Other agencies with significant homeland security responsibilities include the departments of Health and Human Services, Justice, and Energy.

Saturation fire is a saturation attack using an intense level of artillery bombardment or rapid direct fire (from automatic weapons such as machine guns, autocannons or rotary guns) that is designed to overwhelm a target area with lethal firepower, for the purpose of suppression, area denial or mass destruction of the enemy.

Chemical warfare (CW) involves using the toxic properties of chemical substances as weapons. This type of warfare is distinct from nuclear warfare, biological warfare and radiological warfare, which together make up CBRN, the military acronym for chemical, biological, radiological, and nuclear (warfare or weapons), all of which are considered "weapons of mass destruction" (WMDs), a term that contrasts with conventional weapons.

The use of chemical weapons in international armed conflicts is prohibited under international humanitarian law by the 1925 Geneva Protocol and the Hague Conventions of 1899 and 1907. The 1993 Chemical Weapons Convention prohibits signatories from acquiring, stockpiling, developing, and using chemical weapons in all circumstances except for very limited purposes (research, medical, pharmaceutical or protective).

The Soviet atomic bomb project was authorized by Joseph Stalin in the Soviet Union to develop nuclear weapons during and after World War II.

Russian physicist Georgy Flyorov suspected that the Allied powers were secretly developing a "superweapon" since 1939. Flyorov urged Stalin to start a nuclear program in 1942. Early efforts mostly consisted of research at Laboratory No. 2 in Moscow, and intelligence gathering of Soviet-sympathizing atomic spies in the US Manhattan Project. Subsequent efforts involved plutonium production at Mayak in Chelyabinsk and weapon research and assembly at KB-11 in Sarov.

Conventional weapons or conventional arms are weapons whose damaging impact comes from kinetic, incendiary, or explosive energy. They stand in contrast to weapons of mass destruction (e.g., nuclear, biological, radiological, and chemical weapons).

Conflict escalation is the process by which conflicts grow in severity or scale over time. That may refer to conflicts between individuals or groups in interpersonal relationships, or it may refer to the escalation of hostilities in a political or military context. In systems theory, the process of conflict escalation is modeled by positive feedback. Conflict escalation can be modeled with game theory. In contrast, de-escalation are approaches which lead to a decrease or end of a conflict.

While the word escalation was used as early as in 1938, it was popularized during the Cold War by two important books: On Escalation (Herman Kahn, 1965) and Escalation and the Nuclear Option (Bernard Brodie, 1966). In those contexts, it especially referred to war between two major states with weapons of mass destruction during the Cold War.