Trump is again threatening the Iran; interesting to read what he twittered six years ago at the same topic there:
BTW: it is now quite certain why the USA feel so threatened by Iran.
Iran has mounted short range rockets on small motor boats. In a scenario where a swarm of those motor boats is trying to attack an air craft carrier, the air craft carrier always looses, because you cannot eliminate this swarm threat in a fast and reliable kind of fashion.
Of course the evidence is fantastic as ever, when the USA do feel threatened.
Anyway, the strategy makes sense. More important though is the fear, that using those boats the Iran might interrupt the oil deliveries hailing from Saudi Arabia. Oil is still quite cheap, because KSA as an American ally is producing so much, that it intentionallly hurts countries which do depend on oil income like Venezuela, Russia or Iran. Of course if this would be gone, oil price would rise and that's the second fear.
So this is why at the moment Trump is going so much against Iran. BTW, if Saudia Arabias oil exports would stop, the gas price in the USA would increase as well, because the shale oil capacity of refineries in the USA cannot satisfy the domestic gas demand alone.