That's the problem. No one knows for sure. Shipping is extremely risk averse. Who is going to test to see if its a bluff when you are dealing with millions of dollars in ships and cargo. It's not the first time Iran has mined the Strait. So, they do have a track record of being that crazy. There are also rogue actors. Command and Control has been fractured and the IRGC command, what's left of them, don't have control over all the forces in the country.