The new figure, revealed by the Defense Department during a budget hearing on Capitol Hill, is about $4 billion higher than the estimate offered by Defense Secretary Pete Hegseth two weeks ago.

Hegseth and General Dan Caine, chairman of the Joint Chiefs of Staff, were testifying on a $1.5 trillion budget request for 2027 alongside Pentagon finance chief Jules Hurst III when they were asked for an update on the war's price tag.

"At the time of testimony... it was $25 billion," Hurst told lawmakers, referring to Hegseth's April 29 estimate.

"But the joint staff team and the comptroller team are constantly looking at that estimate, and so now we think it's closer to 29," he said -- citing updated "repair and replacement of equipment costs" and broader operational expenses.

Pressed on when Congress would receive a fuller accounting of the war's costs, Hegseth said the administration would request "whatever we think we need" separately from the main Pentagon budget, but did not say when that supplemental request would arrive.

The testimony came as a fragile US-Iran ceasefire appeared increasingly shaky, with Trump warning Monday that the truce was on "life support" after rejecting Tehran's latest peace proposal.

Democrats used the hearing to hammer the administration over both the ballooning cost of the war and what they described as a lack of transparency about US objectives.

"The question must be answered at the end: what have we accomplished and at what cost?" asked Rosa DeLauro, the top Democrat on the House Appropriations Committee.

- 'Lack of transparency' -

Fellow Democrat Betty McCollum accused the Pentagon of a "consistent lack of transparency" and demanded more clarity about the administration's long-term strategy before Congress approves additional funding.

The war has intensified concerns over rapidly depleting US weapons stockpiles after months of heavy missile and air-defense operations in the Middle East.

Hegseth dismissed warnings that the conflict had dangerously drained American munitions reserves.

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

Democratic Senator Mark Kelly warned over the weekend that inventories of Tomahawk missiles, Patriot interceptors and other advanced systems had been severely drawn down and could take years to replenish, potentially weakening US readiness in any future confrontation with China.

The hearings marked Hegseth's first appearance on Capitol Hill since the White House formally notified Congress that hostilities launched by the United States and Israel against Iran on February 28 had "terminated."

Democrats have repeatedly been blocked by the Republicans as they have introduced measures to rein in Trump's Iran war powers, accusing the president of waging war without proper congressional authorization.

Hegseth and Caine faced a second round of questioning before a Senate panel after their House appearance, and there were protesters at both hearings.

In the Senate, an Iranian-American activist interrupted Hegseth's opening statement to call out: "If you approve this budget, you will complicit in the war crimes of this administration."

Senators raised questions about the Trump administration's plan to withdraw 5,000 troops from Germany, which has faced bipartisan pushback.

Hegseth did not comment directly on Washington's relations with Berlin, but said: "It's not the troops. It's the capitals of those militaries that limit what they're able to do, where they're able to go, who they're able to fight, that create limits on our own."