While Ridley Scott’s Alien (1979) functions as a metaphor for rape and birth, James Cameron’s Aliens (1986) is arguably an allegory of the Vietnam War. Before the release of The Terminator (1983), Cameron expressed interest in developing a sequel to Alien, but it was only after the success of The Terminator that the director and producer Gale Ann Hurd received the go ahead to create a sequel that, according to the Aliens Special Edition Audio Commentary, would focus “more on terror, less on horror.”
Beside the deeply sexual imagery, which is prevalent throughout the franchise, the second installment has overtones of imperialism. The Marines are working on behalf of the Weyland-Yutani Corporation to fight the indigenous alien race of planet LV-426, where human colonization has begun. Although the Marines are far more technologically advanced than the Xenomorphs, the extraterrestrial species has a strong knowledge of the landscape and the determination to protect what is theirs. “Their training and technology are inappropriate for the specifics, and that can be seen as analogous to the inability of the superior American firepower to conquer the unseen enemy in Vietnam: a lot of firepower and very little wisdom, and it didn’t work,” Cameron stated. The Marines' gung-ho attitude echoes hard-line US conservative hawks during the Vietnam War, while the Xenomorphs share many similarities with the Vietcong, who fought desperately and unconventionally to repel a foreign invasion.
Just as the US became involved militarily in Vietnam for questionable, convulted reasons, in Aliens the Marines are hired to protect the business interests of their employers by any means necessary. Also like in the real-life conflict, Weyland-Yutani representative Carter Burke (Paul Reiser), Lieutenant Gorman (William Hope) and his men underestimate the resilience of the natives and come to realize that victory may not be as easy as they believed.
Cameron has also said that he used details from the Vietnam war to make the military operations feel grounded in realism and closer to the present, rather than futuristic. He told Jean-Marc and Randy Lofficier, "The dialog[ue] itself, the idiom, is pretty much Vietnam era. It's the most contemporary American combat 'warspeak' that I had access to. I studied how soldiers talked in Vietnam, and I took certain specific bits of terminology, and a general sense of how they express themselves, and I used that for the dialogue, to try and make it seem like a realistic sort of military expedition, as opposed to a high tech, futuristic one. I wanted to create more of a sense of realism rather than that of an interesting future."
Cameron's allusions to the Vietnam conflict, then, were an attempt to make the Aliens story speak to recent history and feel relevant to its audience. The choice was also driven by the concern of counterbalancing the Sci Fi aspects of the film. In order to make the characters feel at home 150 years in the future, Cameron told Lofficier that he focused on projecting our known reality into that world and not pushing the futuristic updates to an extreme. "If you're trying to create a textural reality within a film, you can't go to the extreme of suggesting what technology will be like," he said. "You have to keep it one step beyond what it currently is, but no more, so that you can look at it and say, 'Right, that's a TV set! It's a futuristic TV set, but I know what that is.'"
Cameron also looked to Vietnam vets as inspiration to create Ripley's (Sigourney Weaver) motivation to return to fight the Aliens despite the trauma she has experienced. "One of my biggest problems writing the film was coming up with a reason why she goes back," he told Lofficier. "It had to be psychological. One of the things that interested me is that there are a lot of soldiers from Vietnam, who have been in intense combat situations, who re-enlisted to go back again. Because they had these psychological problems that they had to work out. It's like an inner demon to be exorcised. That was a good metaphor for her character."
It's debatable to what extent Cameron intended the whole film to be read as an allegory of the Vietnam War, but the war's events and its character left an undeniable imprint on the message and atmosphere of Aliens.