The Pentagon has disclosed that the cost of the ongoing war with Iran has risen to nearly $29 billion, intensifying scrutiny over the conflict and its impact on US military readiness.

The figure was revealed on Tuesday during a Defense Department budget hearing on Capitol Hill and is about $4 billion higher than the estimate given by Defense Secretary Pete Hegseth two weeks earlier.

Pentagon finance chief Jules Hurst III told lawmakers that the revised figure reflects updated assessments of operational spending and equipment replacement costs.

“At the time of testimony… it was $25 billion dollars,” Hurst said, adding that “the joint staff team and the comptroller team are constantly looking at that estimate, and so now we think it’s closer to 29.”

Hegseth, alongside General Dan Caine, Chairman of the Joint Chiefs of Staff, was appearing before lawmakers to defend a $1.5 trillion defence budget request for 2027.

Pressed on when Congress would receive a full breakdown of war-related spending, Hegseth said any additional funding request would be submitted separately but did not provide a timeline.

The testimony comes amid growing uncertainty over a fragile US-Iran ceasefire, with President Donald Trump warning that the truce is on “life support” following Tehran’s latest peace proposal.

Democratic lawmakers used the hearing to question both the rising costs and what they described as a lack of transparency regarding US objectives in the conflict.

“The question must be answered at the end — what have we accomplished and at what cost?” asked Congresswoman Rosa DeLauro.

Another lawmaker, Betty McCollum, accused the Pentagon of failing to provide adequate clarity on its long-term strategy.

The war has also raised concerns about the depletion of US weapons stockpiles after months of sustained missile and air defence operations in the Middle East.

However, Hegseth dismissed claims that US munitions reserves were under strain.

“The munitions issue has been foolishly and unhelpfully overstated,” he said. “We know exactly what we have. We have plenty of what we need.”

Senator Mark Kelly warned that inventories of key weapons systems, including Tomahawk missiles and Patriot interceptors, had been significantly reduced and could take years to replenish.

The hearing marked Hegseth’s first appearance before Congress since the White House notified lawmakers that US and Israeli military actions against Iran had officially ended in February.

Some lawmakers have continued to question the legality of the conflict, alleging that the administration proceeded without proper congressional authorisation.