In the Terminator storyline, Skynet was originally installed by the military to control the national arsenal on August 4, 1997. On August 29 it gained self-awareness[1], and the panicking operators, realizing the extent of its abilities, tried to pull the plug. Skynet perceived the attempt to deactivate it as an attack and came to the conclusion that all of humanity would attempt to destroy it. To defend itself, it determined that humanity should be exterminated.

Before it could be deactivated, Skynet launched nuclear missiles under its command at Russia, to which Russia responded by firing many of its missiles back at the United States and its allies. As a result of the nuclear exchange, over three billion humans were killed in just minutes.

During this time, Skynet used its remaining resources to gather a slave labor force from surviving humans. These slaves constructed the first of its automated factories, which acted as the base for its agenda. Within decades, Skynet had established a global presence and used its mechanized units to track down, collect, and dispose of the human survivors.