!!!RED ALERT 3!!!why it need internet connection?

[I Hate Lazy People]

It's for the stupid DRM protections. The game requires the Internet connection to register RA3 to your computer, so you can't install it on a bunch of other computers. The publisher put that crap in there to protect themselves against software pirates. Leave it to EA to screw over paying customers.

See if you can get a free dial-up service to activate the software. It only needs to connect to the internet one time, then you won't need the internet anymore unless you use multiplayer.