Iran has very competent engineers and scientists. They have nuclear fuel and know how to separate U235 and Plutonium. The basic designs of crude nuclear weapons are available in your local library. Iran thus has a functional nuclear weapon if they desire it. Do they have sophisticated small weapons is an unknown. Small thermonuclear weapons are important as to ease of delivery and total yield. The last is an unknown. Do they have nuclear weapons is a known. If they have the designs from North Korea of which they have collaborated with, they have small effectively delivered thermonuclear weapons if North Korea’s thermocunclear weapons have been minturized as those of the USA, Britain, France and Russia.
I forgot to add is Israels policy called the “Samson Option.” Just a few thermonuclear weapons would take out Israel as a functioning society. Israel could lose all their land-based missiles and aircraft and still destroy an enemy via sub launched thermonuclear weapons. Vengeance would rise from the seas.
There would be no winners. Just death and destruction.