There is no question that Israel has penetrated Iran in the sense of getting good intelligence on which to act. How this has been accomplished is one of those Mossad secrets, and I’m certainly not privy to them. But I can certainly speculate.
One thing many people may not realize is that Jews have a very long history in Iran (originally Persia):
The history of the Jews in Iran dates back to late biblical times (mid-1st millennium BCE). The biblical books of Chronicles, Isaiah, Daniel, Ezra, Nehemiah, contain references to the life and experiences of Jews in Persia. In the book of Ezra, the Persian kings are credited with permitting and enabling the Jews to return to Jerusalem and rebuild their Temple; its reconstruction was carried out “according to the decree of Cyrus, and Darius, and Artaxerxes king of Persia” (Ezra 6:14). This event in Jewish history took place in the late 6th century BCE, by which time there was a well-established and influential Jewish community in Persia.
As I said, a long history. I’ll skip to recent history; here’s an article written in February of 2025:
Despite rising antisemitism and diminishing tolerance, Iran’s Jewish community maintains a strong sense of cultural pride and national identity, according to David Nissan, an Iran expert and former Israeli intelligence officer who was born and raised in Tehran. …
When asked to shed light on Iran’s Jewish community, once the flagship of Middle Eastern Jewish communities, Nissan noted that despite significant emigration from the 1979 Islamic Revolution to the present day, the community still maintains a complete Jewish way of life. …
The main challenge for the Jewish community today is separating Zionism from Judaism,” said Nissan.
“They must prominently demonstrate this separation and prove their loyalty to Iran, which views Zionism as illegitimate and reprehensible. The difficult economic situation in Iran also affects the Jewish community, most of which already belongs to a lower socioeconomic status,” he explained. …
Following the revolution, the Jewish community, which at its peak included almost 100,000 Jews, shrunk to just 9,000 Jews currently residing in Tehran, Shiraz and Isfahan.
So these are mostly poor – and I would guess predominantly elderly – Jews whose ancestors probably have been in Iran for millennia and who are not Zionists and must make that clear. I doubt that they are a significant source of the intelligence Israel gets on Iran, although of course I don’t know for sure.
But note the first paragraph I quoted, which is that the speaker, Nissan, is “an Iran expert and former Israeli intelligence officer who was born and raised in Tehran.” So this “former Israeli intelligence officer” is an Iranian expat, and there are many such expats in Israel today. I would guess that some of them are the source of the Mossad’s intelligence on Iran, either by being on the ground undercover in Iran and/or by communicating with Iranian informants who are not Jewish but who are insiders in the government.
Which brings us to the second source of information and I would guess the largest one: Iranian insiders who are not in tune with the mullahcracy and who are giving the Israelis important information on the movement and location of important government figures as well as nuclear scientists, munitions, and plans.
In addition, there is also the usual electronic surveillance. The Israelis are no doubt adept in the most modern versions of that.
The entire apparatus must strike some sort of fear into the Iranian rulers. It’s a sort of “Santa Claus Is Coming to Town” – not that the Iranians are necessarily familiar with that jingle, but “He sees you when you’re sleeping/He knows when you’re awake” must be the way they feel right about now. Plus, note the first line of the song: “You better watch out.”
