The United States acts. Iran threatens.

Does Iran even have the means to blockade the strait?

So as the US warships are effectively blocking the Iranian ports, the Iranians and proxies are threatening to attack ships and close other straits. The question really is whether or not Iran has any ability to do so. The strait is somewhere between 20-30 miles wide. That is a lot of ground to cover without a navy or an air force or even any real means to locate these ships. Will they dare to go out with their speedboats and challenge the American Destroyers in hope of shooting some guns at international tankers.

The reality is that Iran controls the strait only to the degree that they can convince people to fear them. The question is whether or not their bluster is going to prevent ships from avoiding Iranian ports and sailing elsewhere? I suspect that this is one of those situations where once a few tankers start to get through without problems that more will follow. The other problem is that in the long term, these Iranian solutions becomes less and less practical. Reality is that there is other oil in the world that will not be as hard to go get. There are other ways to move the oil (through pipelines and such) that becomes more practical (or even necessary) if the threats continue. The more Iran lashes out, the more likely it is that people will come up with different options. There is no good long term solution for Iran here if their only plan is to illegally hold shipping lanes by force.

Now the reason that they had gotten away with much of this in the past is that they are actually just bullies. They had a decent size military, but more importantly they were willing to use it and nobody seemed willing to stand up to them. Obviously that is not the case anymore. They ran into someone willing to stand up to them in Benjamin Netanyahu and they ran into a much bigger bully in Donald Trump, who carries a much bigger stick. Now they find themselves largely defanged and their only card they have to play is fear. Will it be enough?