The US could flood the area with SSNs, SSGNs, and wipe out the JMSDF. Just need carriers to provide cover from the Japanese P-3C fleet, which is the best in the world, including the US, they are more advanced, just can’t launch SLAM-ER like the US ones, and there are less of them. The carrier air wing will destroy the Japanese air force, even with F-15J, and F-2, they don’t have active AAM, even if they did, I don’t think the Japanese planes have the avionics to use the missiles at their full potential like the Superbugs can. A final note, the most powerful ships in the JMSDF inventory is the Kongo class DDG. The USN has more than 40 of such ships and they can launch Tomahawks.