Battle Los Angeles gave us our first look at the aliens who trash L.A.!

Aaron Eckhart's new movie Battle: Los Angeles tries combine the realistic urban warfare of Black Hawk Down with the classic alien invasion film. We got our first glimpse at crazy battle footage - including a glimpse of those aliens. Spoilers...

The stars of Battle: L.A., Aaron Eckhart and Michelle Rodriguez, came to Comic Con along with director Jonathan Liebesman and producer Neal Moritz. And they showed a ton of new footage:

The footage opens with a little background on the 1942 Battle of Los Angeles, when anti-aircraft artillery responded to reports of an unknown aircraft. It then switches to a more modern-day Los Angeles, clearly under enemy fire, although the nature of the fire isn't entirely clear. As the military evacuates LA, a Marine platoon is ordered to find a group of survivors and bring them back to the evacuation point. But time is short; the Armed Forces plan to bomb LA in just three hours, hoping to obliterate the invading army. The Marines clearly know little about these invaders, except that they are "not of this world."

As the Marines track down the survivors' signal, they are ambushed. We aren't able to see the enemy, although they don't appear to be much taller than humans. Their alienness is betrayed by their gunfire. Most of this footage looks far more like something out of a Iraq War movie than a science fiction film, but the gunfire resembles something out of a laser gun, as if to remind us that we're dealing with extraterrestrials.

We only get the barest flashes of the alien invaders. We occasionally get a glimpse of something sand-colored, a foot taller than any human they encounter, wearing a round, flat helmet. It is not clear at first whether they are entirely biological, or partially mechanical, but it is very clear that they are soldiers. The only hint we get of the aliens' anatomy is when a group of Marines rip one open, looking for weaknesses. And even then, we only see its chest: tough, stringy tendons that are torn apart.

We get a better look at the alien ships. These are messily mechanical monstrosities, obviously built for function over form. The smaller ships vaguely resemble Serenity from Firefly, but there are also larger ships that more closely resemble flying saucers.

On the panel, Jonathan Liebesman talked about trying to make the aliens feel like a real invading army:

That was one of the challenges we faced in the movie. What I love about James Cameron is that all of his designs are functional - they all look like they could work. [These] aliens have an army, generals, medics, lieutenants. We wanted to make it look like they could work.

And Liebesman talked up the aliens' weird design:

We wanted to do an alien that wasn't an insect or a creature. Ridley Scott in Alien really pioneered these fantastic creatures, and in District 9 we got these great insects. We wanted to do something that was literally alien... They have a hint of biomechanicalness to them.

In a separate press conference about the film, Moritz clarified that the aliens are attacking all across the U.S., but we just see the invasion from the vantage point of one Marine battalion in L.A. This ground-up view of the attack gives a "fresh twist on the genre" of alien invasion.

And Eckhart told the press conference that the destruction of L.A. in the movie is massive and awe-inspiring. There were freeways shut down, with cars littered across them, and bombs going off everywhere. "We shot so many rounds it was insane." He added:

When I met Jonathan for the first time, we sat in a room in L.A., and Jonathan had this beautiful display on his computer. He pulled something up on Youtubem and it was Marines fighting in Fallujah, house to house, and he said, "That's what I want the film to look like." I said, "I'm in." We made an urban combat movie with aliens... They put us in boot camp for three weeks where we ate together, slept together, showered together, called each other names [and] shared rations... Neal and Jonathan really gave us the tools to make it real.

Said Moritz, "Early on in the process, we were very conscious that we were taking two genres, a war movie and an alien movie, and combining them." Liebesman shot a short demo film that convinced everybody that those two genres could be combined successfully.

Liebesman told the press conference the destruction of L.A. isn't depicted in terms of landmarks — the aliens aren't using "Wikipedia Travel" to look for monuments to wipe out, like the Hollywood sign. They're looking to wreck the city as a city.

Rodriguez revealed at the press conference that her character wasn't in the script until right before filming — Moritz had promised to put her in another movie if he killed her off in Resident Evil 4. And they needed someone to provide intelligence, so her character, a geeky tech sergeant, was added. Rodriguez is less of a fighter and more of an intel person in this movie — but she does kick ass "in a cool, geeky way," she adds.

So why are the aliens coming to Earth in the first place? Liebesman explains: "Earth is 70 percent water. The aliens in our movie use water for may different things, so they are here for those natural resources."