1) You use the term Jew as a synonym for Israel, but the two are not the same. There are 5.7 million Jewish citizens of Israel and 5.2 million US Jewish citizens. Iran with nukes is not an "existential threat" to Jews; just to Israel. 2) If Israel needs to use her nukes to protect herself- use them!!!
Magnitude 6.1 quake hits Panama-Colombia border (Reuters)
from the article: Lieberman: Israel's interests come first in dealing with Iran threat