TEL AVIV — A debate is raging in Israel between those who believe the country missed a prime opportunity presented by the extensive protests in Iran to bring about regime change in Tehran, and those who argue that the days of the Iranian leadership are numbered regardless.

"This round [following the December protests] is probably over, but the campaign is not," a senior Israeli security official told Al-Monitor on condition of anonymity. "They may have succeeded in stopping the protests using unprecedented violence, but the days of the Iranian leadership are undoubtedly numbered. We would be blind not to realize that it cannot continue for long."

The official's remarks echo those of Prime Minister Benjamin Netanyahu during a Knesset debate on Monday. “No one can predict what tomorrow will bring in Iran, but one thing is clear: No matter what happens, Iran will not return to being what it was.” He also warned that if the Islamic Republic attacks Israel, “We will act with might that Iran has not seen before.”

Economic grievances and growing anti-regime sentiment fueled the protests, prompting a heavy security crackdown by Iranian security forces. Death toll estimates have ranged from 3,000 to 12,000. The US-based Human Rights Activists News Agency said Sunday it has verified at least 3,919 deaths. Reuters on Sunday cited an unnamed Iranian official putting the toll at a minimum of 5,000. Supreme Leader Ayatollah Ali Khamenei acknowledged on Saturday that thousands had been killed, without providing a specific figure. Last Thursday, US President Donald Trump said Iran had halted the killing and planned execution of protesters, stepping back from his earlier threats to attack Iran to stop the violence.