Why it would be a big mistake for the US to go to war with Iran

Reports of a growing US naval presence in the Gulf have prompted speculation that the US could be preparing for another Middle East war, this time with Iran.

The US president, Donald Trump, has warned of “serious consequences” if Iran does not comply with his demands to permanently halt uranium enrichment, curb its ballistic missile program and end support for regional proxy groups.

Yet, despite the familiar language of escalation, much of what is unfolding appears closer to brinkmanship than preparation for war.

The US president’s own political history offers an important starting point for understanding why this is. Trump’s electoral appeal, both in 2016 and again in 2024, has rested heavily on a promise to end America’s “forever wars” and to avoid costly overseas interventions.

And Iran represents the very definition of such a war. Any all-out conflict with Tehran would almost certainly be long and drag in other countries in the region.

It would also be hard to achieve a decisive victory. For a president whose political brand is built on restraint abroad and disruption at home, a war with Iran would contradict the central logic of his foreign policy narrative.

Meanwhile Iran’s strategic posture is rooted in decades of preparing for precisely this scenario. Since the 1979 revolution, Tehran’s military doctrine and foreign policy have been shaped by survival in the face of potential external attack.

Rather than building a conventional force able to defeat the US in open combat, Iran has invested in asymmetric capabilities: ballistic and cruise missiles, the use of regional proxies, cyber operations and anti-access strategies (including missiles, air defences, naval mines, fast attack craft, drones and electronic warfare capabilities). Anyone who attacks Iran would face prolonged and escalating costs.

This is why comparisons to Iraq in 2003 are misleading. Iran is larger, more populous, more internally cohesive and far more militarily prepared for a sustained confrontation.

An attack on Iranian territory would not represent the opening phase of regime collapse but the final layer of a defensive strategy that anticipates exactly such a scenario. Tehran would be prepared to absorb damage and is capable of inflicting it across multiple theatres – including in Iraq, the Gulf, Yemen and beyond.

With an annual defence budget approaching US$900 billion (£650 billion), there is no question that the US has the capacity to initiate a conflict with Iran. But the challenge for the US lies not in starting a war, but in sustaining one.

The wars in Iraq and Afghanistan offer a cautionary precedent. Together, they are estimated to have cost the US between US$6 and and US$8 trillion when long-term veterans’ care, interest payments and reconstruction are included.

These conflicts stretched over decades, repeatedly exceeded initial cost projections and contributed to ballooning public debt. A war with Iran – larger, more capable and more regionally embedded – would almost certainly follow a similar, if not more expensive, trajectory.

The opportunity cost of the conflicts in Iraq and Afghanistan were potentially greater, absorbing vast financial and political capital at a moment when the global balance of power was beginning to shift.

As the US focused on counterinsurgency and stabilisation operations, other powers, notably China and India, were investing heavily in infrastructure, technology and long-term economic growth.

That dynamic is even more pronounced today. The international system is entering a far more intense phase of multipolar rivalry, characterised not only by military competition but by races in artificial intelligence, advanced manufacturing and strategic technologies.

Sustained military engagement in the Middle East would risk locking the US into resource-draining distractions just as competition with China accelerates and emerging powers seek greater influence.

Iran’s geographic position compounds this risk. Sitting astride key global energy routes, Tehran has the ability to disrupt shipping through the Strait of Hormuz.

Even limited disruption would drive oil prices sharply higher, feeding inflation globally. For the US, this would translate into higher consumer prices and reduced economic resilience at precisely the moment when strategic focus and economic stability are most needed.

There is also a danger that military pressure would backfire politically. Despite significant domestic dissatisfaction, the Iranian regime has repeatedly demonstrated its ability to mobilise nationalist sentiment in response to external threats. Military action could strengthen internal cohesion, reinforce the regime’s narrative of resistance and marginalise opposition movements.

Previous US and Israeli strikes on Iranian infrastructure have not produced decisive strategic outcomes. Despite losses of facilities and senior personnel, Iran’s broader military posture and regional influence have proved adaptable.

Rhetoric and restraint

Trump has repeatedly signalled his desire to be recognised as a peacemaker. He has framed his Middle East approach as deterrence without entanglement, citing the Abraham Accords and the absence of large-scale wars during his presidency. This sits uneasily alongside the prospect of war with Iran, particularly the week after the US president launched his “Board of Peace”.

The Abraham Accords depend on regional stability, economic cooperation and investment. A war with Iran would jeopardise all of these. Despite their own rivalry with Tehran, Gulf states such as Saudi Arabia, the UAE and Qatar have prioritised regional de-escalation.

Recent experience in Iraq and Syria shows why. The collapse of central authority created power vacuums quickly filled by terrorist groups, exporting instability rather than peace.

Some argue that Iran’s internal unrest presents a strategic opportunity for external pressure. While the Islamic Republic faces genuine domestic challenges, including economic hardship and social discontent, this should not be confused with imminent collapse. The regime retains powerful security institutions and loyal constituencies, particularly when framed as defending national sovereignty.

Taken together, these factors suggest that current US military movements and rhetoric are better understood as coercive signalling rather than preparation for invasion.

This is not 2003, and Iran is neither Iraq nor Venezuela. A war would not be swift, cheap or decisive. The greatest danger lies not in a deliberate decision to invade, but in miscalculation. Heightened rhetoric and military proximity can increase the risk of accidents and unintended escalation.

Avoiding that outcome will require restraint, diplomacy and a clear recognition that some wars – however loudly threatened – are simply too costly to fight.

Bamo Nouri does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.