UFOs? 'Killer robots'? Zombies? The Department of Defense has you covered “Killer robots are infinitely brave” said John Pike, Global Security's director

 -- That just-revealed secret Pentagon program investigating UFOs isn't the only time the Defense Department has planned for scenarios that might seem better-suited for a science fiction movie.

A few years ago, the DoD had a training “plan” to deal with a “zombie apocalypse.”

An unclassified document CONPLAN 8888 from the U.S. Strategic Command outlined a training exercise — to stave off the walking dead.

Titled CONPLAN 8888, the goal was to develop a comprehensive military strategy to keep “non-zombie” humans from being consumed by a zombie horde.

A Pentagon spokesperson told ABC News CONPLAN 8888 was designed solely as a 2011 in-house training exercise in which students learned basic concepts of military planning for a fictional attack — in this case — a “zombie apocalypse.”

“This dated document is not, and has never been, a U.S. Strategic Command plan,” Maj. Brian Maguire said.

John Pike, an expert on defense, space and intelligence policy and the director of GlobalSecurity.org, said the “zombie” plans used a fictional adversary in order to avoid naming real adversaries such as North Korea or China.

At the same time, Pike said, the Pentagon does have a real-world plan for dealing with robots.

It’s known as the robotic and autonomous system (RAS) and according to Pike, RAS may help the U.S. Army with one of its most pressing battlefield challenges.

While a fully-autonomous "killer robot" has not yet been developed, Pike said, advances in technology are making that closer to reality.

“Killer robots are infinitely brave,” Pike said. “They have no pity and would follow orders. They would aim and fire at the adversary. Humans only shoot in the general direction of their target and they’re afraid to hurt people. Robots shoot to kill.”

Jacob Cohn, Researcher Fellow at the Center for Strategic and Budgetary Assessments, said there is no prediction when autonomous technology may be exerted.

"Semi-autonomous weapons are already in use on battlefields," Cohn said. "But, autonomous weapons may act and react faster than a human would."

There are no killer robot plans developed for countries on the U.S. radar, Pike said, but he noted the government avoids revealing secret plans involving countries like North Korea, China and Russia.

According to Pike, technology like killer robots involves “Moore’s Law --Moore’s law which states that overall computer processing power doubles every two years.

“We have technology like Siri in the palm of our hands. This technology is no longer miraculous, it is normal,” Pike said.