While the aircraft carriers are impressive, they will just act as the centerpiece for their group, and director for its antimissile defenses.
There is a huge area around a carrier within their impressively high powered detection equipment, not just radar, and any threats that enter that area are instantly targeted.
Typically they are designed that, with their group, they can create a very “layered” defense, that is extremely hard to penetrate.
And they are likely supported underwater by some incredibly deadly submarines. In this case motivated that there should never be another Cheonan incident from a NorK sub.
Hopefully a slow moving freighter doesn’t sneak up on them.