Supersonic, nuclear tipped cavitating torpedos.
Once nukes are used, the exchange almost certainly escalates, and those in power on both sides lose (along with many millions of their people). I don’t think either China or Russia wants to go nuclear against us or against each other, and a conventional supercavitating torpedo still has to hit. That technology is not decisive in the carrier battle because you have to get within range not just to shoot but to shoot accurately, i.e., within ten miles. My money is still on the carrier battle group (including cruisers and destroyers with air defense capabilities and one or more SSN escorts).