WASHINGTON (States News) — Members of Congress have not formally authorized a war in Iran, though they may soon be expected to approve emergency funding for the endeavor without any projection from the Trump administration as to how long it may last or the full cost, not just in dollars but in American troop and civilian lives.

Experts on defense spending interviewed by States Newsroom say the cost of weeks of air bombing will mount into the billions of dollars, a sum that will balloon if ground troops are sent into Iran to undertake regime change and if the war extends for months to come.

Defense Department officials briefed Congress on Monday that the Pentagon spent $5.6 billion on munitions alone during the first two days of the war, according to a congressional aide not authorized to speak publicly. The aide expects DOD has spent into the double digits in the days since.

President Donald Trump has sent mixed signals about the timeline and end goals for the war, called Operation Epic Fury. He at first said the bombing campaign he began alongside the Israeli government could last between four and six weeks and on Monday said it is possible it will end “quickly.” Trump, however, hasn’t ruled out a longer assault or the deployment of ground troops.

Republican lawmakers who control Congress say the ongoing attack is an essential national security undertaking and that they won’t constrain Trump in his role as commander-in-chief.

Democrats, who tried unsuccessfully to remove U.S. troops from hostilities until approved by Congress, will be needed to provide enough votes to move any supplemental spending request through the Senate — one possible obstacle to a prolonged conflict.

Even a relatively brief war will have long-lasting, far-reaching consequences for the millions of people pulled into the conflict.

“One lesson of history is that a war that is supposedly short or brief has these huge repercussions that ripple across time,” said Stephanie Savell, director of the Cost of War project at the Watson School of International & Public Affairs at Brown University.

Neither the White House nor the Office of Management and Budget have disclosed publicly how much the bombing has cost taxpayers so far or how much spending it might eventually require. A Defense Department spokesperson said they “have nothing to provide on this at this time.” The top Democrat on the House Budget Committee, Rep. Brendan Boyle of Pennsylvania, has asked the Congressional Budget Office to come up with a number.

Comparison with Iraq, Afghanistan

Michael O’Hanlon, director of research in the foreign policy program at the liberal-leaning Brookings Institution, said a ballpark estimate for the military costs of war during an “extended air campaign” would normally run a couple of billion dollars a month.

“But at this point, I think we’re more likely in the couple billion a week range,” he said.

Achieving long-lasting regime change, which Trump has spoken about often since the war began, could be much more costly, both in terms of American spending and troops’ lives, as well as civilian casualties.

The wars in Afghanistan and Iraq averaged about $1 million per deployed U.S. troop per year once all of the infrastructure, equipment, health care and other factors were rolled into the cost of war.

During the peak of those wars, O’Hanlon said, there were about 100,000 to 175,000 troops in those two countries and the United States was spending about $200 billion annually.

“If you needed at least 100,000 U.S. troops in Afghanistan, you could conceivably need a quarter million or more in Iran if you’re really going to try to occupy and stabilize the whole country,” he said. “So that means now you’re getting into the range of $250 to $300 billion a year for a presence that would stay in Iran for a full 12 months. And then each and every year it would be additional.”

That, however, is just the potential cost for the military. It doesn’t include damage to U.S. diplomatic facilities in the region or other costs associated with war.

“You’ve got your infrastructure damage as well as higher energy costs around the world. And already talk of less fertilizer being produced, which is going to reduce crop yields,” O’Hanlon said. “So there are all sorts of second-order effects.”

‘Wars are never quick or cheap or easy’

The death toll for U.S. troops, seven of whom have already died, could also increase depending on the scope of the conflict.

There were about 150 combat fatalities during the first Gulf War in the early 1990s, as well as about 150 deaths from training and accidents in the lead-up and aftermath, O’Hanlon said.

The war in Afghanistan led to the deaths of about 2,500 U.S. troops across roughly two decades. About 4,500 Americans died in the 15 years of the war in Iraq, he said.

Savell, of the Cost of War program at Brown University, said research has shown that “wars are never quick or cheap or easy.”

The Iraq War that began in 2003, she said, is one of many examples of political leaders messaging ahead of time that a conflict would be “short and decisive and relatively inexpensive.”

“We see many of those kinds of narratives being, you know, a refrain these days in relation to Iran as well,” Savell said. “So I think that the comparison in that sense is apt.”

The Iraq war also had major unanticipated consequences for those living in the region, including “that the U.S. invasion was partially responsible for the rise of the Islamic State,” Savell said.

“And that militant group has now spread its terror attacks around the world,” she said.

In addition to the direct deaths of both troops and civilians that come from bullets, bombs and other weapons of war, there will be indirect deaths that stem from a lack of clean water, food and medical care.

“Those kinds of things have really, really long-lasting and deep impacts for people, especially women and children,” Savell said. “In contemporary wars, children ages zero to five are often the ones who end up suffering in the long term because of the diseases and the malnutrition that can be a reverberating effect of war.”

Regime change ambitions

Seth G. Jones, president of the defense and security department at the Center for Strategic and International Studies, said during a roundtable discussion that he believes it will be “very difficult” for the U.S. and Israeli militaries to cause “major damage to the Iranian regime largely from air and naval assets.”

“I think even with ground troops, trying to social engineer a foreign government is incredibly difficult,” he said.

The U.S. military’s wars in Afghanistan and Iraq, as well as operations in Libya, he said, all used a combination of tactics, including ground forces.

“Those wars persisted for years, if not decades, after that. And we saw civil wars in all three cases and insurgencies,” Jones said. “So, trying to do that without a meaningful ground presence, I think, is going to be virtually impossible. And then you run the risk of what the U.S. did in 1991 in Iraq and Hungary in 1956, which is it urged individuals to rise up, and they were slaughtered in both cases, the Kurds and the Hungarians.”

Shaping an entirely new Iranian regime, he said, would take “months if not longer.”

A prolonged conflict could lead to several challenges for the U.S. military, one of which will be restocking munitions like the Terminal High Altitude Area Defense, or THAAD, about a quarter of which were drawn down in 2025, according to Jones.

“The more the U.S. fires, the less munitions it has, offensive and defensive, including

available for its war plans … against China in the Taiwan Strait, against North Korea on the Korean Peninsula and against Russia,” Jones said.

There is also a chance the conflict could widen even further if Iranian supporters outside of that country decide to begin targeting the U.S. military or civilians.

“Do the Houthis start firing from Yemen? Do we see Iraqi Shia militia start conducting attacks, including against U.S. forces in Syria, Iraq, Jordan, or other locations?” Jones said. “Or do we see the Islamic Revolutionary Guards Quds Force and its partners conduct attacks elsewhere? We know they’ve conducted assassination plots, at least, in the U.S., including in the city of Washington. So how does that expand?”

The defense budget

Mara Karlin, visiting fellow at the Brookings Institution and a professor of practice at Johns Hopkins University’s School of Advanced International Studies, said during a panel discussionthat while the U.S. military has a large budget, its resources aren’t infinite.

Congress approved $838.7 billion for the Department of Defense in January as part of its annual government funding process. Republicans approved another $150 billion for the Pentagon to spend on specific programs, like air and missile defense, as well as shipbuilding, in their “big, beautiful” law enacted in 2025.

“Fundamentally, the U.S. military can often find ways to walk and chew gum; it just gets really hard to do so and the costs can only increase,” she said.

And while the possibility of Trump sending in U.S. ground forces isn’t completely out of the picture, Karlin said that “is almost inconceivable.”

“Ground troops mean you’re getting ready for a lot of casualties, especially given that you have the potential for regime collapse,” she said.

Making that type of choice, to put U.S. troops into Iran, would likely ensure the war “will be long and it will be ugly,” despite the possibility of significant change.

“Iraq 2026 actually looks pretty different. The costs to get to that from 2003 onward were so extraordinarily high,” Karlin said. “And I think that it is safe to assume that if one were to use that analogy, you would see something as rough, if not much, much worse.”