WASHINGTON — After a Jan. 28 drone strike by an Iranian-backed Iraqi militia killed three American soldiers in Jordan, President Joe Biden mourned the loss of “three brave souls in an attack on one of our bases” — and vowed to “respond” with force to deter further deadly misconduct.

But according to analysts who spoke with the Register, it’s difficult to judge which methods of deterrence are likely to work against a longtime U.S. adversary like Iran — and equally difficult to discern whether these actions are morally justified in the fraught current context of the Israel-Hamas conflict in Gaza. 

So far, the American response has been measured. Within days of the deadly attack in Jordan, a U.S.-led military coalition struck remote bases operated by Iran and its proxies in Iraq and Syria. The Pentagon also approved a round of airstrikes on Houthi rebel targets in Yemen, following the Iran-allied militia’s stepped-up threats to international trade and U.S. Navy operations in the Red Sea since the Gaza conflict erupted. 

More broadly, the Biden administration is seeking to deter a swathe of militia groups, which  constitute Iran’s so-called “axis of resistance,” from pursuing their violent campaign to dissuade Washington from supporting Israel’s ground war in Gaza against Hamas. 

But a Houthi official insisted publicly after the air strikes in a post on X that his group would only halt its activities when a permanent ceasefire was secured in Gaza. And on Feb. 5, an Iran-backed militia in Syria signaled that it, too, was not put off by the U.S. counterattacks, when it fired a drone strike near an American military base, killing six fighters from a Washington-allied Kurdish militia.

NBC News reported on Feb. 15 that the U.S. had launched a cyberattack on a suspected Iranian spy ship, operating in the Red Sea and the Gulf of Aden. The Iranian ship had allegedly provided information on cargo ships to the Houthis, but U.S. government did not confirm NBC’s report.

Biden and his advisors are reportedly considering an array of additional military options to deter Iranian-sponsored aggression as Tehran’s shadow war with Washington continues. 

Experts have proposed strikes on Iranian weapons production facilities, ships and intelligence systems. And Congressional Republicans have pressed Biden to consider even more aggressive actions such as direct strikes on Iranian positions and commanders in the region, possibly even on Iranian territory.

Assessing such options from a Catholic perspective, analysts say three central questions come into play: What exactly is deterrence; what is a proportionate U.S. response to Iran’s support of deadly attacks against American troops; and how should the threat of military escalation factor into the choice of the most effective actions?

 

The Morality of Deterrence

“What we are talking about is a strange situation,” said Edward Barrett, director of research at the U.S. Naval Academy’s Stockdale Center for Ethical Leadership, and the author of Persons and Liberal Democracy: The Ethical and Political Thought of Karol Wojtyla/John Paul II.

“We usually think of deterrence as a threat to use force. But you can also think of deterrence as the use of force to deter somebody to not act in the future, or even as coercion — to stop what they are doing” right now.

Barrett told the Register that the debate over Biden’s response to Iran and its proxies does not hinge on the morality of the Pentagon’s present practice of retaliatory strikes, which can be described as appropriately “defensive.” 

Likewise, Msgr. Stuart Swetland, the president of Donnelly College in Kansas and an expert regarding Catholic teaching on the conduct of war, echoed this point, while distinguishing between the Church’s moral evaluation of conventional deterrence and nuclear deterrence. 

“As Gaudium et Spes 80 taught: ‘Every act of war directed to the indiscriminate destruction of whole cities or vast areas with their inhabitants is a crime against God and man, which merits firm and unequivocal condemnation,” Msgr. Swetland told the Register

By contrast, conventional deterrence reflects a “nation’s intention to demonstrate that aggression by other actors will never advance the cause of the aggressor and will always be met with legitimate defense.” As the Catechism of the Catholic Church communicates (2265), such a response to aggression is “both morally upright and a grave duty required of the leaders of nations,” Msgr. Swetland noted.

 

An Art, Not a Science?

At the same time, policymakers note that a credible deterrence policy involves a good deal more than retaliatory strikes to prevent an adversary from planning a future attack. Indeed, in the corridors of power, the practice of deterrence is often viewed as more of an art than a science. There is a psychological and emotional component to the process, which generally begins with political rhetoric and verbal threats, frequently followed by economic sanctions, and the diplomatic isolation of an adversary. 

Biden and his presidential predecessors have adopted some or all of these instruments at various times, in a bid to discourage Iranian interference in the Middle East.

Barrett described the U.S.’s military present strategy regarding Iran and its proxies as one of “escalation dominance: We are trying to use force to deter the Houthis ... by responding in a way that stops the activity, but also allows the other side to save face. You hit back hard, indicating you are willing potentially to go even further, past the point that would be acceptable to them. But you leave them some sense of reputation. So if they respond in a small way afterward, you let it go.”

He noted that the Pentagon followed a similar approach when President Donald Trump approved a 2020 precision strike that killed a top Iranian general, Qasem Soleimani, but did nothing further when Iran reacted.

At the time, the Trump administration had adopted a policy of “maximum pressure” on Iran, and after the general’s death, the administration described the risky and controversial operation as a defensive move, rather than an act of aggression. 

Trump told reporters that Soleimani was planning “imminent and sinister attacks” on Americans, and so the decision to “terminate” him was intended to deter these future attacks.

 

Escalation and Proportionality 

Biden has repeatedly expressed his fear that a strong response from the U.S. could provoke further aggression from Iran, potentially triggering a direct confrontation between Tehran and Washington that would have dire consequences. 

And Barrett agreed that prudence and extreme caution were required. 

Some military proposals advocated by experts are potentially “escalatory,” said Barrett, and must be guided by international law and just-war criteria that require only a proportionate response to unjust aggression, and one that also protects non-combatants. 

If the U.S. were certain the Iranians were directly responsible for the recent attacks on U.S. personnel, he said, it might be justifiable to respond directly against Iran with military force.

“But if we knew that doing so would result in escalation that failed to comply with the just-war criteria of reasonable chance of success and/or wide proportionality, then decision-makers would need to think twice about that action,” Barrett said.

Fear of escalation, he added, “may also explain why we are focusing on the benefactors, not the sponsors” of terror in the Middle East.

Critics of Biden’s Middle East policy counter that its middling results arise from the president’s failure to both decimate the proxy militias and apply sufficient pressure on Iran to pull its support. 

“Iran’s proxies are responsible for more than 150 illegal attacks and counting against U,S. personnel in Iraq and Syria since Oct. 7, and for persistent strikes against U.S. warships and civilian vessels in the Red Sea,” said Sen. Mitch McConnell, R-Ky, in a speech from the Senate floor on Jan. 25, days before the three Americans were killed in Jordan. 

“We have yet to see signs that the U.S. knows how to compel Iran and its proxies to stop.” 

But others point out that while Biden and his presidential predecessors have adopted a range of tactics to discourage Iranian interference in the Middle East, there is wide agreement that collectively they haven’t met their mark. 

“In deterrence, the easiest way to see if something is working or not is observed behavior,” Dakota Wood, a senior research fellow with the Heritage Foundation and a U.S. Marine Corp veteran, told the Register. 

“Since the Iranian revolution in 1978, that regime has been sanctioned and labeled a ‘pariah state.’ But they have become a nuclear power despite the sanctions, and they have extended their ideology.” 

 

Biden’s Dilemma 

Greg Reichberg, research professor at the Peace Research Institute in Oslo and a member of the Pontifical Academy of Social Sciences, underscored the complexity of maintaining a credible U.S. deterrence, especially in a region like the Middle East. 

Deterrence is a “communicative act: applying military force to send a message,” Reichberg told the Register. 

“This is no simple matter because it depends not only on the sender but also the receiver. “Some ‘realists’ speak as though pain is pain, so hit them hard and they’ll get the message. But this is dangerously simplistic.” 

For example, Washington may view an armed U.S. response to a prior attack as a straightforward effort to dissuade the Iranians from launching future attacks, but the effectiveness of the “message” hinges on a number of factors, he said.

First, “Do the Iranians think they have direct control of the proxy force that carried out the attack in Jordan? The U.S. leadership believes they do, but let’s say that’s not the case — just as the Iranians have long believed Israel is a U.S. proxy, but does the U.S effectively control Israel?”

In this scenario, he suggested, the “Iranians will believe the U.S. retaliatory attack is unwarranted or excessive. Then they will feel obliged to restore deterrence vis-à-vis the U.S. by mounting a new attack of their own,” because deterrence is “a two-way street.” 

With these possibilities in mind, Reichberg said, President Biden faces a “dilemma”: “Respond not at all or do too little, [and] the Iranians could be emboldened. But respond too strongly and they might feel obliged to respond in kind, throwing fire into an already inflammatory Middle East.”