TEHERAN (NYTIMES) - The raid alone was brazen enough. A team of Israeli commandos with high-powered torches blasted their way into a vault of a heavily guarded warehouse deep in Iran and made off before dawn with 5,000 pages of top secret papers on the country's nuclear program.

Then in a television broadcast a few weeks later, in April 2018, Israeli Prime Minister Benjamin Netanyahu cited the contents of the pilfered documents and coyly hinted at equally bold operations still to come.

"Remember that name," he said, singling out scientist Mohsen Fakhrizadeh as the captain of Iran's covert attempts to assemble a nuclear weapon.

Now Fakhrizadeh has become the latest casualty in a campaign of audacious covert attacks seemingly designed to torment Iranian leaders with reminders of their weakness.

The operations are confronting Iran with an agonising choice between embracing the demands of hard-liners for swift retaliation, or attempting to make a fresh start with the less implacably hostile administration of President-elect Joe Biden.

Trailed by a carload of bodyguards, Fakhrizadeh on Friday was driving a carefully circuitous route to the home of his in-laws in the city of Absard, Iran, according to witnesses and the Iranian news media.

An empty Nissan parked at a roundabout exploded, knocking down a power line. Gunmen leapt from a parked Hyundai Santa Fe, others arrived on motorcycles, and waiting snipers filled out a hit team of 12 assassins, according to a detailed account posted online by Javad Mogouyi, a documentary filmmaker for Iran's Revolutionary Guard.

Fakhrizadeh, hit with at least three bullets, tumbled from his car and fell bleeding on the ground. The nearest medical clinic had lost electrical power. Roadside cameras were disabled. All 12 assassins escaped unharmed, and Fakhrizadeh was pronounced dead by the time a rescue helicopter was able to transport him to a Tehran hospital.

"It was like a Hollywood action movie," Mogouyi wrote in his account.

It was the latest in a decadelong pattern of mysterious poisonings, car bombings, shootings, thefts and sabotage that has afflicted the Islamic Republic. Most have hit largely anonymous scientists or secretive facilities believed to be linked to its nuclear program, and almost all have been attributed by both US and Iranian officials to Tehran's great nemesis, Israel, whose officials - without formally acknowledging responsibility - have all but openly gloated over the repeated success of their spies.

Never, however, has the Islamic Republic endured a spate of covert attacks quite like in 2020. In January, a U.S. drone strike killed the revered Gen. Qasem Soleimani as he was in a car leaving the Baghdad airport (an attack facilitated by Israel's intelligence, officials say).

And Iran was humiliated in August by an Israeli hit team's fatal shooting of a senior Al-Qaeda leader on the streets of Teheran (this time at the behest of the United States, its officials have said).

Seldom has any country demonstrated a similar ability to strike with apparent impunity inside the territory of its fiercest enemy, said Bruce Riedel, a researcher at the Brookings Institution and a former CIA official with experience in Israel.

"It's unprecedented," he said. "And it shows no sign of being effectively countered by the Iranians." With the killing of their top nuclear scientist as well, Iranians are now grappling with a new sense of vulnerability and demands to purge suspected collaborators. Most of all, they are debating how to respond at a delicate moment.

Iran has endured years of devastating economic sanctions under a campaign of "maximum pressure" from President Donald Trump, and many Iranian leaders are desperately hoping for some measure of relief. Biden has pledged to seek to revive a lapsed agreement that lifted sanctions in exchange for a halt to nuclear research that might produce a weapon.

To pragmatic Iranians, that possibility makes Trump's last months in office no time to lash back and risk renewed hostilities.

But Iranians also know that their enemies in the United States and Israel may take advantage of this period to attack Tehran further. It is a chance to squeeze its leaders between domestic demands for revenge and a pragmatic desire for better relations.

"From today until Trump leaves the White House is the most dangerous period for Iran," Mohammad-Hossein Khoshvaght, a former official at the Ministry of Culture and Guidance, wrote in a message on Twitter.

Retaliation against Israel or Netanyahu's main ally, the United States, would play into the hands of Iran's enemies in the region, Khoshvaght argued. They are seeking "to create a difficult situation," so the new administration cannot revive that nuclear agreement, he added.

Iran first accused Israel of killing one of its scientists when he dropped dead in his laboratory after a poisoning in 2007, and a series of more violent attacks on Iranian scientists between 2010 and 2012 have been widely attributed to Israel as well.

In one, a bomb in a parked motorcycle blew up a particle physicist as he was lowering a garage door at his home in Tehran. In three others, motorcyclists speeding past the moving cars of other scientists slapped magnetic bombs to their car doors, killing two and wounding a third. And in a fifth attack, gunmen on motorcycles sprayed a scientist with bullets while his car was stopped at a traffic light with his wife sitting beside him.

Israel has developed a singularly successful track record in part by concentrating the considerable resources of its spy agencies mainly on Iran, its greatest nemesis, said Riedel of the Brookings Institution.

Israel, he said, has also carefully cultivated ties within countries neighbouring Iran as "platforms" for surveillance and recruitment - most notably in Baku, Azerbaijan. Its recent conflict with Armenia has called attention to drones and other weaponry that Israel has furnished to Azerbaijan as part of that relationship Israel recruits native Farsi speakers from among Iranian immigrants to make contacts or analyse intercepted communications, he added, and Israel has managed to enlist a steady stream of Iranian collaborators.

Now, Riedel argued, the attack on Fakhrizadeh may be an indication that Israel plans other killings. After an eight-year "hiatus" since the wave of assassinations from 2010 to 2012, he said, "I think it is a signal that the game is afoot, or coming."