Could have been a Polish MiG-23, they're members of NATO now so could have been doing exercises in the US.
Incidently, when searching for MiG-23/27 on the internet, it mentions that these MiGs are often confused with the following aircraft: F-111, Tornado, Su-24 Fencer, Mirage F1, Super Etendard, Jaguar. Since it was a NAS it could have been a Argentine Super Etendard since I do know that the US and Argentine Navy often conduct excercises together and allow aicraft to land on each others CVs. Just a guess anyway.
I've seen the ground attack version of the MiG-23 (former East German) at the Flugwerft Schleißheim museum in Munich. Very nice and smallish aircraft.
Here's a couple of pics I took of it:

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