Why are we so excited about alien invasions all of a sudden?S

This is the year of alien invasion. After superheroes, alien invaders might be the most popular media trope of the year. They're dominating movies like Cowboys & Aliens and Battle: Los Angeles and TV shows like V and Falling Skies.

Not to mention Joe Cornish's Attack The Block and Timur Bekmambetov's Darkest Hour. And there are a number of other alien invasion movies and shows in development, from directors like Eli Roth and Nacho Vigalondo. And Warner Bros. is developing All You Need Is Kill. After being a dead genre for years, alien invasions are back. But what's it all about?

One answer is obvious: the alien invasion is just another variation of the post-apocalyptic story. If you get sick of zombies, plagues and eco-catastrophes, you can always swap them out for evil E.T.s. But only an alien invasion story lets us talk about the nature of asymmetric warfare, which is the war of our present – and probably, our future.

Top image: War of the Worlds concept art by Ryan Church.

Alien invasion movies used to be about spies and saboteurs, especially during their 1950s heyday. The aliens were frequently meant to make us think of the "Red Menace" — the fear of Communist infiltrators, who were going to destroy America from within. (In particular, the original Invasion of the Body Snatchers is frequently seen as a metaphor for Communist brainwashing/infiltration.)

Why are we so excited about alien invasions all of a sudden?S

But more recently, things like Independence Day, War of the Worlds and Battle: LA have proved that alien invasion films can be more like war movies. Except that they're usually war movies where the attack comes by surprise and the first assault is almost unstoppable. And it's probably no coincidence that the shift towards "alien invasions as war stories" came after the end of the Cold War, when we started thinking more about situations where one side is a superpower and the other side... isn't.

Asymmetric warfare: when you're outgunned and outmatched

Asymmetric warfare is nothing new, of course. It's been around as long as war, and most wars throughout history have involves one side that's less powerful than the other side. Writers as diverse as Herodotus, Sun Tzu and Clausewitz have commented on the nature of battles that are slanted in one side's favor. But the term "asymmetric warfare" has really only come into fashion in the past 15 years, especially since the phrase appeared in the U.S.' National Security Strategy in 1997. Especially in pop culture, portrayals of war prior to the 1990s involved opponents that were at least somewhat evenly matched, the way the two sides in World War II or the Cold War were.

Why are we so excited about alien invasions all of a sudden?S

There's a great essay about asymmetric warfare in the Sept./Oct. 2001 issue of Military Review, which predicts that we'll see more fighters learning the lesson of the Persian Gulf war, that conventional war against American forces is useless. That magazine probably hit the stands just a few days before the Sept. 11 attacks, which started people thinking, in more earnest, about what people who are outgunned or outclassed might resort to.

(Terrorism, of course, is just one tactic of asymmetric warfare. Others include sabotage, guerilla warfare and civil disobedience.)

Most analyses of asymmetric warfare are explicitly about the United States facing a less equipped foe, such as is currently the case in Afghanistan and Iraq. The U.S.' current working definition of asymmetric warfare goes:

Asymmetric approaches are attempts to circumvent or undermine US strengths while exploiting US weaknesses using methods that differ significantly from the United States' expected method of operations. [Asymmetric approaches] generally seek a major psychological impact, such as shock or confusion that affects an opponentís initiative, freedom of action, or will. Asymmetric methods require an appreciation of an opponent's vulnerabilities. Asymmetric approaches often employ innovative, nontraditional tactics, weapons, or technologies, and can be applied at all levels of warfare — strategic, operational, and tactical — and across the spectrum of military operations.

The more people use the term, the more they start to apply it to different situations — such as the Indian resistance to the British Empire in the 18th Century, the American Revolutionary War, and so on. But it usually comes back to the current situation of the United States, facing counter-insurgencies and non-traditional methods of fighting.

Why science fiction loves asymmetric warfare

Why are we so excited about alien invasions all of a sudden?S

The most classic depiction of asymmetric battle, as currently conceived of, probably appears in James Cameron's Avatar, in which the humans have massively superior technology to the bows and arrows wielded by the indigenous Na'Vi. The Na'Vi don't really resort to sabotage or guerilla tactics, although there is a certain amount of cunning in their assault on the Dragon at the end of the film. But Avatar drives home the message that technological superiority doesn't guarantee a victory — especially when you go and piss off the great tree spirit.

But in most pop culture depictions of lopsided war, "we" are the Na'Vi. (And by "we," I mean "Americans," since these movies and TV shows are made in the U.S.) Alien invasions are one of the main ways that we're able to think about being on the receiving end of an overwhelming assault from a superior foe — basically, being in the position that we've been putting others into.

Why would we want to watch stories about being the underdog? Well, the "underdog" thing is an attraction in its own right. Nobody really wants to root for the overwhelming forces that are crushing all resistance — you'd rather root for the wily resistance fighters who fight back using raw cunning and unconventional methods. It's just more dramatically interesting.

Plus to some extent, these kinds of stories bring up the same kind of wish fulfillment as other post-apocalyptic stories: you get to imagine being one of the few survivors. The resistance fighters are heroic and awesome, so there's escapism in picturing yourself as one of them. Etc. etc.

Why are we so excited about alien invasions all of a sudden?S

But also, we know, deep down, that we may one day be on the other side of this equation, that the United States won't be the world's main superpower forever. Past superpowers have often only realized their new status when they suddenly faced a sudden, damaging assault from a rising power. Plus, as the main power on the receiving end of asymmetric warfare, we can't really understand it unless we see it from the other side.

Science fiction is also uniquely suited to talking about the realities of post-Cold War fighting, because so much of asymmetric warfare deals with a technological superiority on one side. The idea of how you cope with a technological strategic advantage is one that science fiction can easily dramatize, because alien technologies are automatically going to be awesome and incomprehensible. (And on the real side, any alien race with the ability to travel interstellar distances to visit Earth is going to be massively more powerful than we are.)

And when you talk about the kinds of scenarios that strategic planners discuss for future asymmetric warfare, you quickly stray into science fiction territory anyway. Like, if an enemy managed to detonate a nuclear bomb in the upper atmosphere over Nebraska, the attackers would probably manage to knock out unshielded electronics across most of the continental United States with almost no loss of life.

This sort of thing could be the future of warfare — thanks to UAVs and other drones, war is only going to get more asymmetric, and the methods used by the less-equipped side are only going to get more extreme and insane. Good thing we have science fiction to prepare us. After all, if Harrison Ford on a horse can withstand an attack by spaceships, then there's hope for all of us.