Iranian security guards’ careless use of mobile phones over several years played a central role in allowing Israeli military intelligence to hunt Iranian nuclear scientists and military commanders, The New York Times said on Sunday quoting Iranian and Israeli officials.

Israel had been tracking senior Iranian nuclear scientists since the end of 2022 and had weighed killing them as early as last October but held off to avoid a clash with the Biden administration, the Israeli officials told the newspaper.

The Times said it was June 16, the fourth day of Iran’s war with Israel, and Iran’s Supreme National Security Council gathered for an emergency meeting in a bunker 100 feet below a mountain slope in the western part of Tehran.

It noted that the meeting was so secret that only the attendees, a handful of top Iranian government officials and military commanders, knew the time and location.

The account of Israel’s strike on the meeting, and the details of how it tracked and targeted Iranian officials and commanders, is based on interviews with five senior Iranian officials, two members of the Iranian Revolutionary Guards Corps and nine Israeli military and intelligence officials.

The newspaper said the officials, who included President Masoud Pezeshkian, the heads of the judiciary and the intelligence ministry and senior military commanders, arrived at the meeting in separate cars. None of them carried mobile phones, knowing that Israeli intelligence could track them, NYT wrote.

Despite all the precautions, Israeli jets dropped six bombs on top of the bunker soon after the meeting began, targeting the two entrance and exit doors. Remarkably, nobody in the bunker was killed. When the leaders later made their way out of the bunker, they found the bodies of a few guards, killed by the blasts.

The attack threw Iran’s intelligence apparatus into a tailspin, and soon enough Iranian officials discovered a devastating security lapse: The Israelis had been led to the meeting by hacking the phones of bodyguards who had accompanied the Iranian leaders to the site and waited outside.

Israel’s tracking of the guards has not been previously reported. It was one part of a larger effort to penetrate the most tightly guarded circles of Iran’s security and intelligence apparatus that has had officials in Tehran chasing shadows for two months.

According to Iranian and Israeli officials, Iranian security guards’ careless use of mobile phones over several years – including posting on social media – played a central role in allowing Israeli military intelligence to hunt Iranian nuclear scientists and military commanders and the Israeli Air Force to swoop in and kill them with missiles and bombs during the first week of the June war.

“We know senior officials and commanders did not carry phones, but their interlocutors, security guards and drivers had phones; they did not take precautions seriously, and this is how most of them were traced,” said Sasan Karimi, who previously served as the deputy vice president for strategy in Iran’s current government and is now a political analyst and lecturer at Tehran University.

The security breakdowns with the bodyguards are just one component of what Iranian officials acknowledge has been a long-running and often successful effort by Israel to use spies and operatives placed around the country as well as technology against Iran, sometimes with devastating effect.

Following the most recent conflict, Iran remains focused on hunting down operatives that it fears remain present in the country and the government, according to The New York Times.

“Infiltration has reached the highest echelons of our decision making,” Mostafa Hashemi Taba, a former vice president and minister, said in an interview with Iranian media in late June.

This month Iran executed a nuclear scientist, Roozbeh Vadi, on allegations of spying for Israel and facilitating the assassination of another scientist.

Three senior Iranian officials and a member of the Revolutionary Guards said Iran had quietly arrested or placed under house arrest dozens of people from the military, intelligence and government branches who were suspected of spying for Israel, some of them high-ranking.

Israel has neither confirmed nor denied a connection to those so accused.

Spy games between Iran and Israel have been a constant feature of a decades-long shadow war between the two countries, and Israel’s success in June in killing so many important Iranian security figures shows just how much Israel has gained the upper hand.

From the end of last year until June, what the Israelis called a “decapitation team” reviewed the files of all the scientists in the Iranian nuclear project known to Israel, to decide which they would recommend to kill.

The first list contained 400 names. That was reduced to 100, mainly based on material from an Iranian nuclear archive that the Mossad, the Israeli intelligence agency, had stolen from Iran in 2018. In the end, Iran said the Israelis focused on and killed 13 scientists.

At the same time, Israel was building its capacity to target and kill senior Iranian military officials under a program called “Operation Red Wedding,” a play on a bloody “Game of Thrones” episode. Brig. Gen. Amir Ali Hajizadeh, the commander of the Revolutionary Guards’ Aerospace Force, was the first target, one Israeli official said.

Ultimately, Israeli officials said, the basic idea in both operations was to locate 20 to 25 human targets in Iran and hit all of them in the opening strike of the campaign, on the assumption that they would be more careful afterward, making them much harder to hit.

In a video interview with an Iranian journalist, the newly appointed head of the Revolutionary Guards Corps, Brig. Gen. Ahmad Vahidi, said that although Israel had human operatives and spies in the country, it had tracked senior officials and scientists and discovered the location of sensitive meetings mostly through advanced technology.

“The enemy gets the majority of its intelligence through technology, satellites and electronic data,” General Vahidi said. “They can find people, get information, their voices, images and zoom in with precise satellites and find the locations.”

Hamzeh Safavi, a political and military analyst whose father is the top military adviser to the supreme leader, Ali Khamenei, said that Israel’s technological superiority over Iran was an existential threat. He said Iran had no choice but to conduct a security shakedown, overhaul its protocols and make difficult decisions – including arrests and prosecution of high-level spies.

“We must do whatever it takes to identify and address this threat; we have a major security and intelligence bug and nothing is more urgent than repairing this hole,” Safavi said in a telephone interview.

From the Israeli side, Iran’s growing awareness of the threat to senior figures came to be seen as an opportunity.

Fearing more assassinations on the ground of the sort that Israel had pulled off successfully in the past, Khamenei ordered extensive security measures including large contingents of bodyguards and warned against the use of mobile phones and messaging apps like WhatsApp, which is commonly used in Iran.

“Using so many bodyguards is a weakness that we imposed on them, and we were able to take advantage of that,” one Israeli defense official said.

Those bodyguards, Israel discovered, were not only carrying cellphones but even posting from them on social media.

Iranian officials had long suspected that Israel was tracking the movements of senior military commanders and nuclear scientists through their mobile phones.

Last year, after Israel detonated bombs hidden inside thousands of pagers carried by Hezbollah operatives in Lebanon, Iran banned many of its officials in particularly sensitive jobs from using smartphones, social media and messaging apps.

The cellphone ban initially did not extend to the security guards protecting the officials, scientists and commanders.

That changed after Israel’s wave of assassinations on the first day of the war. Guards are now supposed to carry only walkie-talkies. Only team leaders who do not travel with the officials can carry cellphones.