By Amit Gupta

July 27, 2026

Amid a pause in Donald J. Trump’s bombing of Iran, the U.S. president is said to be weighing diplomatic and military options in the conflict. But the conclusive victory that Trump advertised — where the regime is removed, Iran gives a binding pledge to not build nuclear weapons, and its missile production capabilities are capped — would likely now require the administration to put boots on the ground in large numbers.

Critics have pointed out the obvious problems with this: Iran’s mountainous terrain makes a land invasion difficult; it is a country of 90 million people, twice the population of Iraq; the Iranians have been planning for this contingency ever since George W. Bush labeled them part of the “Axis of Evil”; and unlike Iraq and Libya, the Iranian military has shown a willingness to fight and inflict casualties.

But there is another problem. America has neither enough ground troops for an invasion some estimate would require more than one million troops, nor the willingness to take sufficient casualties in such a bloody battle. What led to this dilemma and what are the military consequences of it?

Background

America’s Civil War remains the bloodiest conflict in the country’s history and the conservative estimate is that over 650,000 people died in the battle. In World War II, 407,000 Americans died, and by the time the Korean War followed, with 36,000 casualties, cracks were beginning to show in American society about sending troops abroad. The Vietnam War fundamentally changed attitudes as over 58,000 American servicemen were killed and for the first-time television brought a war into the nation’s living rooms.

The “body bag effect”, whereby public intolerance for U.S. casualties in foreign wars became a political factor in military decisions, was born.

Post-Vietnam

After Vietnam, the US military gradually developed a military doctrine based on three premises.  First, conscription would end, and the U.S. military would be an all-volunteer force.  Second, the military increasingly favored the use of high-tech, precision weaponry. The effectiveness of this weaponry was meant to preclude the need for boots on the ground in any future war. Third, given the sensitivities of the American public, future wars were going to be low-casualty conflicts. These three fundamentals of the new force had both advantages and limitations.

In the first Gulf War, the U.S. lost 382 soldiers and casualties were even lower in the Bosnia and Kosovo wars where 12 and two Americans were killed, respectively. The American public was getting used to the all-volunteer force winning easily with few casualties, leading the French military commander in Bosnia to say that, “the U.S. believes in zero-dead wars.”

Then came the terror attack of 9/11.

The Taliban were quickly defeated with a low loss of life, and this encouraged George Bush and the neocons to try and change the political map of the Middle East, starting with the regime of Saddam Hussein. What followed was the second Iraq war, and in the insurgency it provoked, there were 4,500 American casualties along with tens of thousands of walking wounded.

The combined death toll of the Afghanistan and Iraq wars, after 20 years of conflict, was just over 7, 000. This meant about 350 casualties a year. But as the casualty numbers rose, the Bush presidency became increasingly unpopular. The high levels of seriously wounded and those with post-traumatic stress disorder also placed a significant strain on the American budget.

The United States separately funds the veterans’ budget (unlike other countries which include it in the defense budget) and that covers pensions, healthcare, benefits, and war cemeteries. This amount has spiked from $197. 4 billion in 2018 to $488.2 billion for Fiscal Year 2027.  When added to the $1.5 trillion that the Trump administration wants in the defense budget, that means total spending on the armed forces will be around $2 Trillion, a sum which is likely to stretch the limits of American governmental expenditure.

Further, since the Iraq and Afghan wars, the mood in America has been to not get engaged in another brutal land war and one of the reasons Trump was re-elected was that he declared that he would not engage in another major war. Given the American public’s aversion to casualties, what are the implications for American military doctrine and Trump’s use of military force?

Low Casualties and Doctrine

The need to minimize casualties has meant an overreliance on technology to fight wars.  This led to a growing dependence on air and naval power as opposed to the use of land forces. It also led to the mistaken notion both in the U.S. and in NATO that technology could substitute for the use of ground soldiers.

Amid changing public perceptions of combat and conflict, the margin of error for any American president in terms of how many military deaths are acceptable continues to shrink. All other considerations of muddled or absent casus belli and flawed strategy aside, it is this casualty aversion that Trump is faced with.

Iran and the Nuclear Option

For Trump to have followed up the air strikes on Iran with a land invasion would have required close to 200,000 troops and significant casualties. Not surprisingly, polls show that the majority of Americans do not approve of the Iran war and would prefer not to put boots on the ground. Support is waning even among Trump’s MAGA base.

America’s success with high-tech weapons was against weak enemies like Iraq, Syria, Libya, and Venezuela. Iran is a very different opponent.  It has a large population, difficult terrain, control of the Strait of Hormuz, precision weaponry of its own, and most importantly, a population with the will to fight.

Faced by these limitations, the Trump administration has been forced to use air and naval power, which while certainly damaging Iran have not been able to deliver a decisive victory. Further, the Iranians have been able to inflict significant damage on U.S. bases in the region as well as hit radar installations and aircraft that are vital for air superiority.

Despite Trump’s talk about using nuclear weapons, the U.S. military has, according to one source essentially vetoed the use of these systems. Prosecuting the war with the old Pentagon playbook is not working since the Iranians have used the benefits of geography as well as American reluctance to engage in a full-scale conflict to resist U.S. military pressure.

Reports that Defense Secretary Pete Hegseth would like to reintroduce conscription have been met with widescale public disapproval and Republican congressmen are not going to lose their seats by supporting this measure.

So, the Trump administration will have to seek a diplomatic solution, but this is complicated by Israeli intransigence and an Iranian unwillingness to concede on certain vital issues such as closing down their ballistic missile program. Nor is there a seasoned diplomat Trump could delegate to conduct serious negotiations with Tehran.

Welcome to the era of modern warfare.

Amit Gupta is a Non-Resident Fellow with the Forum of Federations, Ottawa, Canada. He served for 20 years on the faculty of the USAF Air War College in Montgomery, Alabama. The views expressed in this article are his own.