A quick Google search yielded nothing in that regard... honestly it just doesn't sound that credible in an age where increasingly anyone can say anything. Why believe such a claim without evidence? Because it was the FBI that said it?
There are tempting targets all over the place. Like in the Middle East itself that Iran can barely hit. Their defenses and their leaders are being blown to smithereens. But you want me to believe they might have a submarine off the coast of California?