Iran's increasing regional adventurism shows its vulnerability

If that scenario were to happen, the US would have no choice but to intervene militarily in aid of Israel, which in turn means a direct attack on Iran itself. Within this framework, Iran is already automatically deterred from transforming the conflict between Israel and Hamas into an all-out regional war. 

What Iran and its proxies are doing instead is conducting limited attacks in different countries.

Read more: America's Houthi dilemma: Limited strikes or full-fledged war?

Hezbollah continues to launch rockets on northern Israel, and Israel responds by bombing southern Lebanon. Iran-backed militias in Iraq and Syria attack US bases in both countries, leading the US to counterattack.

The Houthis in Yemen target ships in the Red Sea they claim are connected with Israel, sparking retaliatory strikes on the Houthis by the US and the UK. Notably, both countries gave the Houthis plenty of advance notice before carrying out this retaliation, indicating their interest in minimising the scope of their intervention. 

Iran and its proxies did not stop their limited attacks even after American and British retaliation. And yet the US and the UK continue to invoke the notion of deterrence in relation to their response to those attacks, creating a chain of tit-for-tat military action.

US and UK adherence to describing their responses as "deterrence" while Iran looks like it is ignoring their warnings puts the credibility of deterrence at stake. Iran's stance is linked to its awareness of the priorities and limitations of the US and the UK in the context of the Middle East. 

Iran is aware that the limited reaction by the US and the UK is partly motivated by their desire to de-escalate conflict in the Middle East.

No party benefits from seeing conflict in the region spread and being dragged into all-out war. Such a scenario would not serve their geopolitical interests; it would not advance their influence in the Middle East.

Read more: No regional war over Gaza, but everyone still loses

Other factors

Both countries also expect respective presidential and parliamentary elections to take place later this year, which means they also need to be mindful of domestic priorities.

The scars of the Iraq invasion of 2023 are still being felt by the populations of the US and the UK, and neither sees the benefit in their countries' being involved in costly wars in the region. 

Iran also knows that the continuation of the war in Ukraine is another reason behind the need for the US and the UK to prioritise where military resources go.

The UK's Integrated Review— the country's national security and international strategy — clearly states that the top priority region for the UK in this regard is the Euro-Atlantic, not the Middle East. A similar framework applies to US national security and foreign policy priorities.

Despite the war between Israel and Hamas, the Middle East remains marginal for Washington compared with the geopolitical and economic importance of Europe and the Asia-Pacific region. 

Read more: Biden's security strategy reflects waning US interest in the Middle East

But other dimensions complicate the picture.

A sign of vulnerability

The more Iran and its proxies engage in military adventurism, the greater the margin of risk they are taking. The US and the UK know that countries and entities taking high risks are usually motivated by fear of losing an already fragile status.

So rather than interpreting the continuation of the attacks by Iran and its proxies as an expression of assertiveness vis-à-vis the US and its allies, the US and the UK also see this continuation as an indication of a degree of vulnerability on Iran's side. 

This vulnerability is driven by both domestic and foreign dynamics.

No matter how hard Iran has been cracking down on oppositional voices domestically, the persistence of expressions of dissent against the ruling regime is a continuing source of headache for Tehran — especially at a time when a firm decision on succession after the death of the current Supreme Leader Ali Khamenei has not yet been made.

On the external front, Iran is seeing in the potential for a decisive diplomatic move towards resurrecting the Israel-Palestine peace process following the ongoing war in Gaza a threat to its own stake in the continuation of the conflict. 

Seen through this prism, Iran's attack on Erbil, which showcased the range of its ballistic missiles, is not just an indirect way of letting Israel know that Iranian missiles can reach it but also an illustration of a degree of fear that is driving Iran to put more of its cards on the table.

By the same token, the US does not need to engage in risky behaviour in the Middle East because its status there is pretty firm, regardless of how some actors in the region frame it, such as through calls for the withdrawal of US troops from Iraq and Syria by Iran-backed groups. 

US messages to its public and Israel

The question then here is: If the US is confident about its status in the Middle East and if the notion of deterrence is complicated both because of challenges to credibility and because of prior awareness of Iran's vulnerabilities, why do the US and the UK keep framing their military responses to Iran and its proxies in terms of deterrence? 

One answer is that with elections looming, both countries cannot allow Iran and its proxies to continue with their threats, but both are also trying to reassure their own domestic publics that they are not on the path of engaging in all-out war.

Another answer is that an indirect target of the messaging is Israel.

Emphasising American and British interest in keeping military engagement limited serves to tell the Israeli government to curb its own adventurism and that there is no appetite for the US and the UK to be dragged by Israel towards escalation. 

But the bottom line remains Iran.

Despite all its muscle flexing, Iran is feeling vulnerable. Iran's apparent bravado shows it is geared more towards trying to avert loss rather than seeking gains.