Isn't the Nomad just a big, floating, sitting duck?

Why doesn't East Asian AI culture (or whatever exactly the relevant political unit is) just take it down with missiles etc.? Simply overwhelm whatever anti-missile defensive capabilities it may have with sufficient numbers of simultanenously incoming threats, i.e. the same basic technique you'd use to sink any enemy aircraft carriers that came too close to your coast-line (think too of how the US would respond in a flash to a Nomad-type structure being used against *it*!). There's simply no need for the AIs to spend masses of time and energy inventing a completely new technology (the child/the weapon) , which takes years to grow/deploy which evidently has lots of vulnerabilities and only works at relatively awkward close-range?

Maybe the point is just that if my query is allowed then there is no movie, but I in fact couldn't stop thinking about this problem throughout. Anyone else have this problem?