The last time the United States carried out a major strike against Iran — killing the leader of the country’s elite Quds Force five years ago — the response from the Islamic republic seemed oddly subdued, at least initially.
Iran fired a flurry of missiles that wounded American troops stationed at military bases in Iraq, but fell far short of the vengeance threatened by Iran’s supreme leader, Ayatollah Khamenei, for the death of one of his top lieutenants.
It took years, however, for the full dimensions of Iran’s intended campaign of revenge to come into view. In that time, U.S. authorities uncovered and disrupted a series of assassination plots. The targets, according to U.S. officials and court filings, included former national security adviser John Bolton, former secretary of state Mike Pompeo and Donald Trump, at the time the former president.
The American bombing of Iranian nuclear facilities early Sunday pushed the U.S. conflict with Iran across a dangerous new threshold. U.S. and Western security officials said that they expect Iran to seek to retaliate in ways that eclipse its attempts to avenge the death of Quds leader Qasem Soleimani, and that the U.S. and its allies in Europe and the Middle East face an escalated threat from Iran that could last years.
“It is unthinkable that Iran will not at some point attempt to carry out retaliatory, asymmetric strikes,” said Matthew Levitt, director of the counterterrorism program at the Washington Institute for Near East Policy.
“Their standoff capabilities and nascent nuclear program have been badly hit,” he said, referring to the toll of the U.S. bombings and Israeli operations against Iran’s military leadership and regional proxies including Hezbollah. “But the last tool that remains standing and will be most easily resurrected is their ability to carry out terror plots abroad.”
Tehran has already signaled that it is prepared to use all available means to respond to the U.S. bombing. “Iran reserves all options to defend its sovereignty, interest, and people,” Abbas Araghchi, Iran’s foreign minister, said on social media Sunday. “The events this morning are outrageous and will have everlasting consequences.”
The FBI and its counterparts in Europe and the Middle East were already moving to put more scrutiny on cells and networks with suspected links to Iran, Western security officials said in interviews on Sunday. Several spoke on the condition of anonymity, citing the secrecy around such operations. An FBI spokesperson declined to comment.
Security services had stepped up monitoring of Iranian networks when Israel launched its initial attacks on targets in Iran earlier this month, officials said. Germany and France both added security around synagogues and other Jewish sites, according to media reports.
Those measures have been made more urgent by the U.S. decision to enter the war by sending B-2 bombers to carry out strikes on nuclear sites, including the Fordow uranium enrichment facility, built into a mountain to fortify it against all but the most powerful Earth-penetrating munitions.
Iran also has more conventional response options, especially in the short term, officials said. U.S. military personnel continue to be stationed on bases in Iraq and other locations in the Middle East that are within reach of Iranian ballistic missiles. Iranian-backed Houthi militants in Yemen could also launch fresh attacks on U.S. or allied vessels in the Red Sea.
But those options are likely to be seen as inadequate by Khamenei and his inner circle, said Will Wechsler, senior director of Middle East programs at the Atlantic Council and a former top Pentagon counterterrorism official.
“Iran has a peculiar sense of symmetry and typically a longer time horizon [for planning and pursuing operations] than the United States,” Wechsler said. “The question is when could the asymmetric elements come into play.”
There are also questions about Iran’s capabilities, given the frequency with which alleged Iranian plots and networks have been rolled up in recent years.
The latest case surfaced Saturday, when authorities in Cyprus said they had detained a man who was suspected of working as an Iranian spy and monitoring a U.K. air base.
British authorities arrested seven Iranian nationals last month in raids across the country. Four were detained and then released as part of what British authorities said was an ongoing investigation of an alleged plot to attack the Israeli Embassy in London.
Three others were charged with espionage-related offenses and accused of gathering information about Iran International, a London-based satellite news network that British authorities say has been a target of repeated plots linked to Iran. Home Secretary Yvette Cooper said the arrests were the result of “major operations that reflect some of the biggest counterstate threat and counterterrorism operations that we have seen in recent years.”
At a time when European security services are confronting sabotage attacks by Russian proxies and espionage operations by China, Iran is widely seen as a particularly determined sponsor of violence. The head of Britain’s MI5 domestic security service, Ken McCallum, said last year that the U.K. had faced at least 20 “potentially lethal” plots linked to Iran since 2022.
The vast majority of plots attributed to Iran in Britain and elsewhere in recent years have been thwarted, but the stabbing of a prominent host of a news show for Iran International last year underscored how Tehran had begun turning to criminal syndicates to elude authorities.
The attack was carried out by Romanian nationals who were able to enter Britain without arousing suspicion, monitor journalist Pouria Zeraati and stab him as he sought to enter his car parked outside his home in Wimbledon, officials said. British officials have said the assailants were hired, perhaps unwittingly, by intermediaries for Iran’s security services, and that their decision to stab Zeraati in the leg rather than vital organs suggests that the attack was meant as a signal to silence critics without triggering the fallout that a killing might have caused.
Iran has also turned to criminal networks for operations in the U.S., according to the Justice Department, hiring members of the Hells Angels biker gang in a failed plot to assassinate an Iranian defector living under an assumed identity in Maryland. Soleimani, the target of the 2020 U.S. drone strike, is suspected of overseeing a 2011 plot to hire a member of a Mexican drug cartel to assassinate the Saudi ambassador to the United States at the Georgetown restaurant Cafe Milano.
The failures of these operations, and Iran’s apparent decision to enlist associates of criminal networks, are seen by many officials as evidence of poor tradecraft and mounting desperation by Tehran’s security services. But Iran has been linked to devastating attacks since the early years of the Islamic republic, including the bombing of military barracks in Beirut in 1983 that killed 241 U.S. military personnel, and the subsequent kidnapping and killing of the CIA’s station chief in Beirut, William F. Buckley.
The main targets of Iran’s efforts to avenge Soleimani’s death were senior members of Trump’s first administration, including Pompeo and Bolton. Both subsequently fell out of favor with Trump, who upon returning to office ordered the removal of U.S. security details that had been assigned to protect them.