Target ? Look at it this way - CVN 78 is likely to be much better protected than HMS Queen Elizabeth ever will be.
A US Carrier Strike Group would have at least 1 x Ticonderoga class AEGIS cruiser and 2 or 3 Arleigh Burke class destroyers (or even up to 6 if necessary). That lot easily out trumps (pun intended) a Type 45 - that's if the Type 45 can get out of port and doesn't have to go anywhere too hot ! (banter - I know there is an expensive plot to fix the issues but quantity and multiple defensive missile options have a quality all of their own).
Also, with the current President and SecDef, I don't think there would be any pussyfooting around if someone did attack a 7,500-person unit worth at least $35 Billion (including aircraft but not including the enormous additional cost of missiles on ships) - a significant deterrent effect.
http://i.imgur.com/3rlcMlB.jpg
https://en.wikipedia.org/wiki/Ticonderoga-class_cruiser
https://en.wikipedia.org/wiki/Arleig...lass_destroyer
A US CSG is certainly much less of a target than a RAFG air base would have been had the Cold War gone hot and it has much better systems defending it !