Have to wonder if it’s not just a ploy to apply pressure with an implied threat.
So just for the sake of argument, the Iranians decide to do...what exactly? Sink this container ship? Which one, when, by what means. Have one of their proxies do it for them?
I would think that this sort of military hardware is not shipped commercial, but transported by US Navy ships. So there is no real problem here except that the Iraninas get the idea that we are doing a build-up of arms for a strike on hardened targets.
Frankly, I would be willing to bet that the material has already been delivered by the time news of the contract is leaked if it went commercial.
Prepare. Disperse. Begin deception.
What else does your non-military mind want to know?