Military Expert: The World Could Never Survive a Real 'Battle: Los Angeles'

A giant spaceship from another world arrives during the day and positions itself above the White House in Washington, while more ships do the same over other major cities around the world.

Then, without warning, all hell breaks loose, and the ships begin using devastating weapons and power to destroy everything around them -- people, buildings, military resistance.

This continues for about two hours of popcorn-eating enjoyment until the Earthlings on screen somehow come up with a miracle to stop these unwelcome invaders from laying waste to our beloved planet.

From "The War of the Worlds," "Independence Day," "Mars Attacks!" "Transformers," "Invasion of the Body Snatchers," "The Day the Earth Stood Still," "V" and the current box office favorite, "Battle: Los Angeles," alien invasion is most definitely part of our culture -- and maybe our fears.

But, in the real world, if predatory ETs come to Earth to take us over, for whatever their reasons, could we, in fact, prevent it from happening? Could we actually survive such an attack?

"The bottom line for a hostile engagement between aliens and humans is not a pretty picture, and there is no happy ending for us," according to John Alexander, a retired Army colonel who spent 25 years searching top levels of the U.S. government for evidence of a reported UFO cover-up -- and couldn't find one.