To be fair to SAM (not easy, I know) but about 12 years ago the USN were seriously concerned when the IRGN practiced a Swarm attack against a CVN in the Gulf without warning. Deploying counter measures is OK if you have an expectation of the threat but on this occasion the swarm came from no where & there was no chance of deploying a defensive screen; in such a scenario it is likely that some boats would get through anyway, armed with anti tank weaponry or even as suicide boats packed with explosives.
I guess that vessels transiting the Gulf will need the protection of many friendly fast patrol boats and top cover from AH types, if the threat is considered credible.