Hypersonic missiles that we have no effective counter for.
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Aegis equipped ships have successfully hit ballistic missiles and satellites in testing (and probably under operational conditions as of last weekend), and both of those are, by definition, hypersonic targets. While the US Navy doesn't comment on what weapons a ship might be carrying, it's almost a certainty that all of them have some SM-3s in the magazines at this point.
Our ability to project power is minimal now and it shows in our unwillingness to risk those gold plated targets against any kind of hostile actor that would have a chance of taking them out.
The biggest current problem with the carrier groups projecting power is that their air wings have less combat power than they have had in the past due to both being smaller and composed entirely of strike fighters with relatively short ranges. Using half the Hornets as tankers solves the range problem but makes the availability problem worse in both the short and long terms. The F-35 appears to improve the range situation, shockingly (thought not by enough) and I would expect that, in war time, the Navy would probably augment the air wings significantly (there is definitely room on the decks).
Why do you think those carriers are nowhere near Iran, Taiwan or Kola?
As far as not getting close to anything that can harm them, any nation would be stupid to put its carriers any closer to anything that can shoot at them then it needs to. With that said, Ike is currently operating in the Red Sea where Iran's proxies can shoot at her and TR is currently in the East China Sea where China can shoot at her directly.