Iraq
The second potential response is to ramp up air strikes on Iran-backed armed groups in Iraq. Sunday’s drone strike was claimed by the Islamic Resistance in Iraq (IRI), an umbrella group of militias which has split from the broader Popular Mobilisation Forces. The IRI includes Harakat Hezbollah al-Nujaba, one of the most powerful pro-Iran militias in Iraq, which is believed to be responsible for many of the recent attacks against US forces.
The US has conducted five retaliatory strikes in Iraq in response to previous attacks by the IRI since the war in Gaza began, one of which on January 21 saw two American soldiers stationed at the Asad air base in western Iraq suffer major brain injuries.
But those responses have not delivered, as Sunday’s deadly attack showed all too clearly. “Deterrence was never asserted, and this is the cost – three lost troops and 34 plus injured,” said Charles Lister, senior fellow at the Middle East Institute.
Mark Dubowitz, chief executive of the Foundation for Defense of Democracies, added: “If you want a strike against the regime in Iran that is ‘non-escalatory’ but also ‘effective and deterrent’, Biden needs to wipe out IRGC bases and kill senior IRGC commanders. Only then will Khamenei back down.”
The IRGC in Syria
A more intense response would therefore be to simultaneously conduct strikes in both Iraq and Syria, with action against the IRI in Iraq being combined with moves against sites in Syria belonging to the Iranian Revolutionary Guard Corps (IRGC).
The US has attacked IRGC positions in Syria – where they operate as advisers and trainers to Bashar al Assad’s military and support a number of anti-American militias – three times since October 7. On November 8, US air force jets bombed a weapons depot and four days later they struck a training facility and safe house. Both strikes were conducted in the eastern oil-rich Deir ez-Zour province.
“The US has conceded too large a margin to Iran for proxy attacks,” said Aaron David Miller, a former Middle East peace negotiator and senior fellow at the Carnegie Endowment for International Peace. “Washington needs to reduce that margin and send a tougher message to Tehran for killing Americans – attacks against Iranian forces in Iraq and Syria.”
There are a number of other prominent IRGC sites in Syria, including: a command and control centre called the “glasshouse” at Damascus airport, the Imam Ali air base near the Iraq border, a major drone facility at the Dimas air base near the Lebanon border, and an elite special forces training camp at Mayadin in eastern Syria.
“Bear in mind that as standard practice, Iran will already have evacuated personnel from key sites and senior operatives will have gone to ground,” Mr Lister said. Nevertheless, the US would still be sending a major message of deterrence.
Iran
The most serious option for retaliation would be against Iran itself. Tehran has attempted to distance itself from Sunday’s attack, with Nasser Kanaani, the foreign ministry spokesman, saying on Monday that it does not give orders to “resistance groups”. But Mr Biden was clear in his response on Sunday night that “radical Iran-backed militant groups” were responsible, thereby implicating Tehran as indirectly responsible for the attack.
If the ayatollahs’ arms-length involvement is taken as adequate justification for direct military action, the US could choose to pursue Iranian naval assets. Tehran says it has deployed four naval squadrons to “international waters” since their Houthi allies started attacks on international shipping in the Red Sea. The US Navy is also operating in the region.
Matthew Kroenig, vice president of the Atlantic Council, said the US could also strike Iranian naval bases, nuclear and missile sites, while targeting senior personnel as it did in 2020 when Qassem Soleimani, head of the IRGC’s Quds Force, was assassinated in Iraq.
“Deterrence works by convincing an adversary that the costs to attacking the United States and its allies and interests greatly outweighs any conceivable benefits,” he said, adding that limiting retaliation to its proxy forces “would be read in Tehran as a sign of weakness and simply stoke a continued cycle of violence”.
This retaliation, however, would inevitably trigger an Iranian response. The 21-mile Strait of Hormuz is the world’s most significant oil artery: more than 20 million barrels of crude pass through it every day and 80 million metric tonnes of liquefied natural gas every year, representing 20 per cent of the global supply of both.
If Iran starts striking ships in the strait, or even tries to blockade it entirely, the war could regionalise – bringing in Saudi Arabia, Kuwait and UAE who all export through the Strait – and fuel prices would soar worldwide.
The impact that would have on the average American would be significant at the best of times, let alone in an election year. With Mr Biden almost certain to be taking on the more isolationist Donald Trump in November’s presidential contest, that risk may well convince the White House that strikes on Iran itself are a step too far.
