In an attempt to gain military superiority, Adolf Hitler ordered the development of surface-to-surface missiles among other things. With such a large number of weapons there is a higher chance that the given country would become involved in conflict because they would be more willing to take the chance of fighting a war and the country would be far more aggressive with a high volume of weaponry. .
Vertical proliferation of non-conventional weapons is the internal development of weapons of mass destruction. There are three categories of weapons of mass destruction; nuclear, chemical, and biological. The nuclear bomb the United States dropped on Hiroshima and Nagasaki, Japan was a 12.5-kiloton atomic bomb, "an explosive blast equal to 12,500 tons of conventional high explosives (such as TNT) and caused high pressure waves, flying debris, extreme heat, and radioactive fallout." Examples of chemical weapons would include the nerve agent Sarin that was deployed by a religious cult in Japan in 1995 to kill and injure the general public, and mustard gas that was used during World War I. Biological weapons are far more deadly and destructive compared to chemical weapons; examples of biological weapons are anthrax and the bubonic plague. However with chemical and biological weapons, their effectiveness relies heavily on the accuracy of the delivery system. .
Horizontal proliferation of conventional weapons is the sales, sharing and theft of weaponry between countries. The United States sells more conventional weaponry than any other country in the world. However this becomes a huge problem when a country goes to war with a country that they sold arms to at one point. For example, the war against terrorism in Afghanistan, the Afghan government used artillery against the United States that the United States sold to them when they were fighting the war against Russia; this is referred to as deadly returns.
