[Two Kids' Dad]

Any potential ‘adversary’ capable of interstellar travel would be technologically far superior to us, so tipping our hand really wouldn’t be an issue in that regard.

[waterhill]

What if they are not from outer space, but from underground/ocean?

[Oatka]

Any potential ‘adversary’ capable of interstellar travel would be technologically far superior to us, so tipping our hand really wouldn’t be an issue in that regard.

At a minimum, Cortez vs the Aztecs - or more likely modern military vs the Aztecs.