Iran was "wasting time... not meeting deadlines" on US restrictions overs its nuclear and ballistic missile programmes, Israel Foreign Affairs Minister Gideon Sa'ar told NDTV Monday evening, as he explained the triggers behind joint US-Israel strikes that began 72 hours earlier.
Sa'ar told NDTV US-Israeli intelligence also said Tehran was getting ready to transfer key aspects of nuclear and ballistic missile facilities, technologies, and resources to underground installations - built so deep neither the US nor Israel could effectively strike them from the air.
"Those who conduct the negotiations, the Americans themselves, concluded that Iran, as usual, is wasting time, i.e., not meeting American red lines with regard to the nuclear programme... with regard to the ballistic missiles programme," Sa'ar said.
"(And) we knew that in a very short time Iran was going to put all its nuclear programme details inside very deep underground installations... which not Israel and not America could hit effectively from the air. They planned to do the same thing with ballistic missile production."
Allowing Tehran to transfer such weapons tech to hard-to-access facilities would give the "dangerous Iran regime immunity (to) do whatever they want to", Sa'ar argued, pointing to Iranian missile attacks on other West Asian countries in the past three days as an example.
Iran responded to US-Israel missile attacks by unleashing a torrent of missiles and its low-cost Shahed kamikaze drones at American military bases across West Asia.
For Israel, he continued, Iran represents an "existential threat". Recalling the conflict in June last year, Sa'ar claimed Tehran's strategy had not changed from then.
"The elimination of Israel... and the means for that are terror proxies, nuclear ambitions, and long-range ballistic missiles in huge numbers," he said.
"So, this is why we decided, with our American friends, that we must act. There are, of course, complications... but it's more dangerous not to act rather than to act in this situation."
Sa'aar also spoke about the death of Iran Supreme Leader Ayatollah Ali Khamenei, whom he branded "head of a murderous regime" and linked to terrorist attacks worldwide.
Khamenei was killed Saturday in a missile strike on his compound in central Tehran.
"He was directly involved in terrorism... Argentina just said he ordered actions in Buenos Aires (referring to the bombing of a Jewish community centre in 1994 that killed 85 people). So, he was personally responsible for terrorism worldwide," the Israeli Foreign Minister said.
"And he butchered the Iranian people (referring to civilian protests that began in December 2025). So, I would say he is the head of a murderous regime. From the minute we started to plan this operation we did whatever is necessary to make it (the targeting of Khamenei) successful."
But the assassination of the Ayatollah does not immediately translate into victory. "There are a few dozen heads of this regime that have been eliminated... but they are still in control and are deploying to prevent any kind of public protest that could accelerate a regime change in Iran."
Asked how long could that take - US President Donald Trump claimed four weeks - assuming a successful close to the US' 'Operation Epic Fury' and Israel's 'Operation Roaring Lion', Sa'ar would not comment to a specific timeline. "We will look at the objectives and we will, of course, coordinate things with our American allies," he told NDTV.
Sa'ar was similarly non-committal about the identity of a possible civilian Iranian leader.
"Not Israel (and) not the US will decide who will lead the Iranian people. I think it is for the Iranian people to choose, within a fair and free electoral process," he said.
"But the fair and free election will not happen while this regime is still powerful. So, we need to weaken them to an extent that a transmission is possible. And this is what we aim to do."
