J.G.
Hi V.,
A good way to diffuse the tantrums. Is to stand by and ask him if he is finished, even possibly laugh. Sometimes when they don't get a rise out of you the realize it isn't working and they will stop.
My son tried that a few times and that is exactly what I did, stood by laughed and asked him if he was finished. He realized that he the tantrum wasn't working and he stopped doing it.
Good Luck.