Khamenei Vows Retaliation for Killing of Iran's Top Nuclear Scientist Fakhrizadeh

On Saturday, a day after gunmen ambushed a car near Tehran and killed the man Western and Israeli governments regard as the architect of Iran's secret nuclear weapons effort, the country's supreme leader made a public promise. Ayatollah Ali Khamenei said on Twitter that Iranian officials must take up the task of pursuing the crime and punishing its perpetrators and those who commanded it. He also pledged to continue the work of the dead man, Mohsen Fakhrizadeh.

Fakhrizadeh was ambushed on Friday, and his car was sprayed with bullets. He was rushed to a hospital, where he died. He kept little public profile inside Iran, but outside it his name carried weight. The UN nuclear watchdog, the International Atomic Energy Agency, named him in its 2015 final assessment of open questions about Iran's programme. He was the only Iranian scientist mentioned there, described as overseeing activities in support of a possible military dimension. In 2018, Israeli Prime Minister Benjamin Netanyahu made him central to a presentation accusing Iran of still seeking nuclear weapons. "Remember that name, Fakhrizadeh," Netanyahu said then. Iran says it has never sought nuclear arms.

President Hassan Rouhani was quick to blame Israel. In a televised meeting on Saturday, he said Iran would respond "at the proper time," and he accused "Global Arrogance and the Zionist mercenaries" of staining their hands with the blood of an Iranian son. Those are phrases officials use for Israel. A senior Iranian official told Reuters that retaliation was certain, with timing and method depending on national interests. It might come in days or weeks, he said. He pointed to Iran's missile attack in January on an Iraqi base housing U.S. forces, launched days after a U.S. drone strike in Baghdad killed military commander Qassem Soleimani. No U.S. troops died in that strike. Foreign Minister Mohammad Javad Zarif called it shameful that some refuse to stand against terrorism and hide behind calls for restraint. Germany and UN Secretary-General Antonio Guterres had urged restraint from all sides.

Israel has not claimed the killing. Netanyahu's office declined to comment, and the Foreign Ministry said it does not discuss security at its missions abroad. Cabinet minister Tzachi Hanegbi, a confidant of the prime minister, told N12 he had "no clue" who did it, adding that his silence was not a matter of discretion. Israel's Army Radio reported that some embassies were put on high alert after Iran's threats, though there were no reports of concrete threats, and its military affairs correspondent said the army remained on routine footing. The White House, Pentagon, State Department, CIA and Joe Biden's transition team all declined to comment.

The timing matters because of what Biden hopes to do. He takes office on Jan. 20 and has been expected to try to revive the 2015 nuclear agreement, under which Iran curbed its nuclear work in return for sanctions relief. Donald Trump withdrew from that deal in 2018. Renewed U.S. sanctions cut Iran's vital oil exports and crippled its economy, while Tehran sped up its nuclear work. Amos Yadlin, a former Israeli military intelligence chief, wrote that whether Iran takes revenge or holds back, the killing will make it harder for Biden to return to the agreement.

Fereydoon Abbasi, former head of Iran's Atomic Energy Organisation, who survived an assassination attempt in 2010, said Fakhrizadeh's death would accelerate the nuclear work. At least four scientists were killed between 2010 and 2012 in what Tehran described as a campaign of assassinations meant to sabotage its programme. U.S. intelligence and the IAEA believe Iran halted its coordinated weapons programme in 2003, and the IAEA has said it saw no credible indications of relevant activity after 2009.

One other detail sits near the edges of the story. The United States sent the aircraft carrier Nimitz and accompanying ships to the Gulf on Wednesday, shortly before the killing. A Navy spokeswoman said the deployment was not tied to any specific threats. What to watch now is whether Iran acts in the weeks before Biden's inauguration, and how that shapes any return to diplomacy.