It's not just the US though, every major military power has invested into stealth technology for their ships and planes. From what I've read it's not about whether a plane or ship is detectable or not detectable, it effects the range from which they can be detected, what bands of the EM spectrum they're detectable in, and how easy it is to get a missile lock on them. It's not just a case of making them look smaller on radar.
Well there's only three of 'em, so whatever power they had will be very limited.
I suppose in reality if the Railguns are added, they can simply be seen as sniper units but for the sea, thus far more important job of hitting strategic targets.