Nuclear warfare (sometimes atomic warfare or thermonuclear warfare), is a military conflict or political strategy in which nuclear weaponry is used to inflict damage on an opponent. Compared to conventional warfare, nuclear warfare can be vastly more destructive in range and extent of damage, and in a much shorter time frame. A major nuclear exchange could have severe long-term effects, primarily from radiation release, but also from the production of high levels of atmospheric pollution leading to a "nuclear winter" that could last for decades, centuries, or even millennia after the initial attack.[1][2] A large nuclear war is considered to bear existential risk for civilization on Earth.[3][4] Importantly however, despite modern civilization being at risk, assuming weapons stockpiles at the previous cold war heights, analysts and physicists have found that billions of humans could perhaps survive a global thermonuclear war.[5][6][7][8]
Only two nuclear weapons have been used in the course of warfare, both by the United States near the end of World War II. 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 Nagasaki, Japan. These two bombings resulted in the deaths of approximately 200,000 Japanese people (mostly civilians) from acute injuries sustained in the detonations.[9]
After World War II, nuclear weapons were also developed by the Soviet Union (1949), the United Kingdom (1952), France (1960), and the People's Republic of China (1964), which contributed to the state of conflict and extreme tension that became known as the Cold War. In 1974, India, and in 1998, Pakistan, two countries that were openly hostile toward each other, developed nuclear weapons. Israel (1960s) and North Korea (2006) are also thought to have developed stocks of nuclear weapons, but their Governments have never admitted to having nuclear weapons. South Africa also manufactured several complete nuclear weapons in the 1980s, but subsequently became the first country to voluntarily destroy their domestically made weapons stocks and abandon further production (1990s).[10]
Nuclear weapons have been detonated on over two thousand occasions for testing purposes and demonstrations.[11]
After the collapse of the Soviet Union in 1991 and the resultant end of the Cold War, the threat of a major nuclear war between the two nuclear superpowers was generally thought to have declined. Since then, concern over nuclear weapons has shifted to the prevention of localized nuclear conflicts resulting from nuclear proliferation, and the threat of nuclear terrorism.
Nuclear terrorism by non-state organizations or actors (even individuals) is a largely unknown and understudied factor in nuclear deterrence thinking, as states possessing nuclear weapons are susceptible to retaliation in kind, while sub- or trans-state actors may be less so. The collapse of the Soviet Union has given rise to the possibility that former Soviet nuclear weapons might become available on the black market (so-called 'loose nukes'). While no warheads are known to have been mislaid, it has been alleged that at least some very small or suitcase-size bombs might be unaccounted for.
A number of other concerns have been expressed about the security of nuclear weapons in other, newer nuclear powers with relatively less stable governments, such as Pakistan, but in each case, the fears have been addressed to some extent by statements and evidence provided by those nations, as well as cooperative programs between nations. Worry remains, however, in many circles that a relative decrease in security of nuclear weapons has emerged in recent years, and that terrorists or others may attempt to exert control over (or use) nuclear weapons, militarily applicable technology, or nuclear materials and fuel.
Another possible nuclear terrorism threat are devices designed to disperse radioactive materials over a large area using conventional explosives, called dirty bombs. The detonation of a "dirty bomb" would not cause a nuclear explosion, nor would it release enough radiation to kill or injure a lot of people. However, it could cause severe disruption and require potentially very costly decontamination procedures and increased spending on security measures.
http://en.wikipedia.org/wiki/Nuclear_war
