It’s also good to have some ANZAC fighters closeby or in your US pacific fleet (they can land on a US air craft carrier).
When US troops get ashore somewhere, they can land and give a strong extra defence (in Alpha3),
and on islands where there are airbases already, they can scramble as well.
An accompanying ANZAC destroyer (and/or sub) or 2 can also be of value, in case some risky US attack doesn’t go as planned, the ANZAC units can still fix certain problems (taking out something with a sub/DD + fighters, or blocking enemy fleet if needed).
Anyway, teaming up pays off.