Here is the movie trailer for Battle: Los Angeles.

Battle: Los Angeles revolves around a Marine staff sergeant (Aaron Eckhart) and his new platoon’s battle against an alien invasion on the streets of Los Angeles.

If you do a Google search on “Battle of Los Angeles,” you will find out that in 1942 Los Angeles had a UFO air craft visit them. It was even reported in the LA Times.  You can check out the story here.