I'd imagine that every country with a sub force would describe it as "Sonar Evading". What would the point be, otherwise?
I'd be concerned about this threat. Iran would only need to get lucky, once, and I'd imagine that a shallow, muddied environment like the Persian Gulf is a pretty good place for diesel subs.
Please note that I'm not a submariner, but I did read "Hunt for Red October" while staying at the Holiday Inn last night.
Follow the link under Post #19. Everything you need to know.