An app for phones and computers that lets them come.
A planet involved in an interstellar war that most of the population doesn’t experience because the toltlitarian government is actually doing a decent job of keeping the carnage far from the homeworld, but the cost is a world wide police state. Doubt that there there even is a war is common, as it’s all fought with robots manufactured by the population at the far reaches of the solar system. until two workers evading their duties witness the crash of an alien scout ship. first civilian contact with the ship’s crew calls into question everyone’s assumptions. The enemy looks just like we do, except they are another gender.
[this could be a pretty easy short story, with a twist ending. All we see is male military and in the early 21st century this would still be fairly easy to pass off. There would be a intimations of relationships when a couple of soldiers were off by themselves, slaps on the ass or whatever, slightly more submissive and butch guys, the exposition of how the police state, guy whispering to his honey on the phone, we assume a woman, various hints of the existence of women but never shown. A very rah rah atmosphere, the protection of the homeworld, family etc. Then the ship crashes and the two dudes go to investigate. Just before they are called out they have dialogue agreeing that they are both not like the others, I’ve tried “the sex” but I can take it or leave it, not my cup of tea, like yeah, what’s the big deal? Then when they crack the cabin and discover two space babes they are like whoa, i want to fuck these aliens!]