Of course. But the tale of modern naval warfare suggests that most things catastrophic enough to sink a major warship tend to do so surprisingly quickly and with a high loss of life among those aboard.
The Iranian threat is, of course, their diesel submarines (kilo class). Kilo class subs can, with a dash of luck, be quiet enough to penetrate a carrier screen and take a shot at the carrier. Odds are against this working, of course, but diesel is quieter than nuke.
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