The alien invasion is a common theme in science fiction stories and film, in which extraterrestrials invade Earth either to exterminate or replace human life, enslave it under a system of colonialism, harvest humans for food, steal the planet's resources, or simply just destroy the earth.

The invasion scenario has been used as an allegory for a protest against military hegemony and the societal ills of the time. H.G. Wells' novel The War of the Worlds exploits invasion panics that were common when science fiction was first emerging as a genre.

Prospects of invasion tended to vary with the state of current affairs, and current perceptions of threat. Alien invasion was a common metaphor in U.S. science fiction during the Cold War, illustrating the fears of foreign (e.g. Soviet Union) occupation and nuclear devastation of the American people. Examples of these stories include The Liberation of Earth by William Tenn and The Body Snatchers.

In the invasion trope, fictional aliens contacting Earth tend to either observe (sometimes using experiments) or invade, rather than help the population of Earth acquire the capacity to participate in interplanetary affairs. There have been a few exceptions, such as the alien-initiated first contact that begins the 1951 film The Day the Earth Stood Still, and the Vulcan-initiated first contact that concludes the 1996 film Star Trek: First Contact (although after a failed invasion by the Borg in the rest of the film). In both cases, aliens decide to visit Earth only after noticing that its inhabitants have reached a threshold level of technology: nuclear weapons combined with space travel in the first case, and faster-than-light travel using warp drive technology in the second.

Michio Kaku (加来 道雄, Kaku Michio^?, born January 24, 1947) is an American theoretical physicist, the Henry Semat Professor of Theoretical Physics in the City College of New York of City University of New York, a co-founder of string field theory, a futurist, and a "communicator" and "popularizer" of science. He has written several books about physics and related topics; he has made frequent appearances on radio, television, and film; and he writes extensive online blogs and articles. He has written two New York Times best sellers, Physics of the Impossible (2008) and Physics of the Future (2011). He has hosted several TV specials for BBC-TV, the Discovery Channel, and the Science Channel.

Kaku was born in San Jose, California to Japanese immigrant parents. His grandfather came to the United States to take part in the clean-up operation after the 1906 San Francisco Earthquake^{[citation needed]}. His father was born in California but was educated in Japan and spoke little English. Both his parents were put in the Tule Lake War Relocation Center, where they met and where his two brothers were born.

William Jefferson "Bill" Clinton (born William Jefferson Blythe III; August 19, 1946) is an American politician who served as the 42nd President of the United States from 1993 to 2001. Inaugurated at age 46, he was the third-youngest president. He took office at the end of the Cold War, and was the first president of the baby boomer generation. Clinton has been described as a New Democrat. Many of his policies have been attributed to a centrist Third Way philosophy of governance.

Born and raised in Arkansas, Clinton became both a student leader and a skilled musician. He is an alumnus of Georgetown University where he was Phi Beta Kappa and earned a Rhodes Scholarship to attend the University of Oxford. He is married to Hillary Rodham Clinton, who has served as the United States Secretary of State since 2009 and was a Senator from New York from 2001 to 2009. Both Clintons received law degrees from Yale Law School, where they met and began dating. As Governor of Arkansas, Clinton overhauled the state's education system, and served as Chair of the National Governors Association.