It’s Trump’s War. We’re Stuck With the Bill.

Ms. Brannen is a senior fellow at the Reiss Center on Law and Security at New York University.

Nobody knows what the human or strategic costs of President Trump’s war against Iran will be, but the hard dollar costs are mounting by the day.

A week ago, U.S. Central Command said that more than 50,000 troops, bombers, 200 fighter aircraft and two aircraft carriers are participating in Operation Epic Fury. Our military is burning through munitions, striking thousands of targets and using hundreds of sophisticated — and expensive — defense interceptors and missiles. Last week, three American F-15s were downed over Kuwait in an apparent friendly fire incident. The aircrews were OK, but the aircraft would take at least $300 million to replace.

Elaine McCusker, a top Pentagon official during the first Trump administration, told me she estimates that by the end of its sixth day, the war’s cost exceeded $11 billion, including more than $5 billion worth of interceptors. To replenish its arsenal, the Pentagon is expected to ask Congress for an additional $50 billion. Meanwhile, Mr. Trump wants to add $600 billion to the Pentagon’s annual budget, for a whopping $1.5 trillion in the next fiscal year.

It’s an astronomical tally for a president who returned to office pledging to end wars, not start them. But it’s not just the figure that should unsettle Americans. There’s not much evidence that Mr. Trump’s use of our military to both clean up trash in Washington and arrest and kill foreign leaders is making Americans safer. With three years left in office, he may only be getting started.

The war in Iran is Mr. Trump’s costliest military operation to date, coming after he spent an estimated $2 billion bombing Iran’s nuclear sites last June. Our understanding of the broader costs of the war will emerge with time, but we’re already seeing instability, economic and otherwise: Russia is benefiting from the increase in demand for its oil as world energy prices rise because the conflict has disrupted the shipment and production of oil and gas. Law enforcement agencies in the United States and Europe are on heightened alert for potential terrorist attacks. And Mr. Trump has opened the door for other countries to wage wars of choice and aggression.

In January, Secretary of State Marco Rubio claimed that the administration’s plans for Venezuela are “not going to cost us anything.” But his assertion essentially ignored the money it took to surge air and naval assets to maintain a legally dubious blockade of sanctioned oil tankers since the end of last year and eventually remove its president, Nicolás Maduro.

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