The Iranian President is probably about as sane and rational as the US President. That is, I admit, a worrying thought.

However I'm not aware that he has made any threats about using nuclear weapons against nuclear armed Israel. What he has said is that he would like to see the country wiped off the map - not wiped off the planet, wiped off the map. The same way Palestine was wiped off the map, and more recently the USSR, Czechoslovakia, Yugoslavia, British Honduras, the Gold Coast...

Maps change.