ELINT is very powerful, and the US intelligence agencies have been at this game since before WWII. Their sneakiness boggles the mind! They were using signals bounced off of the moon to spy on Soviet equipment, and disguised the whole thing as radio astronomy!
http://www.youtube.com/watch?v=hFSPHfZQpIQ
If you are going to go up against the US defense establishment, you'd better be damned sure you know what you're doing.
If I were the US, facing such an asymmetric threat, I'd keep most of my carrier groups around for the short term as a boondoggle, then come up with my own novel threat against my opponent's shipping.
(Sub launched cruise missiles, or mines? The advanced 21st century version, of course.)