The decrepit Kilo class submarines are the last of the US/UK/NATO worries. Their positions (two only - one is in port @ Bandar - & incapable of putting to sea) are known by the minute by the US.
How you know this? Only a Kilo has enough firepower to inflict serious damage on a USN carrier, probably. (Stennis = 100,000 tons = big bugg@r)