Earlier this week, NBC News reported that the Defense Department inspector general issued its first report on the war, acknowledging a munitions shortage and saying the cost of the conflict was about $33 billion, excluding the repair of damaged facilities and other costs, as of June 30. A Congressional Budget Office report, issued Tuesday, put the cost of the war at $38 billion and concluded that the conflict was driving up inflation for Americans. Critics of those estimates believe they fail to capture the true costs of the war.

During a Senate Appropriations Committee hearing in late July, Hegseth put the cost of the Iran war so far at $37.5 billion. He said his estimate included payroll, operation, maintenance and other “anticipated” costs through the end of the budget year.

In addition to the true costs of the war, the senators also are requesting a breakdown of the Pentagon’s $67 billion supplemental budget request, as well as an accounting of money spent so far of the roughly $34 billion from the tax and spending bill President Donald Trump signed last year.

In the letter, the senators lamented the lack of public briefings or hearings on the war.

During the first six months of the Iraq War in 2003, then-Defense Secretary Donald Rumsfeld briefed Congress 20 times, and he briefed the media more than 70 times during the first month of that war, the letter says.

“In stark contrast, you have briefed Congress just seven times in that same period and in those appearances, refused to answer basic questions about the objectives and cost of this war,” the letter to Hegseth says.

Hegseth has briefed the Pentagon press corps eight times since the start of the Iran war in February. The last briefing was in May.

During the Iraq and Afghanistan wars, the letter said, the Pentagon regularly asked for additional funding, so-called supplementals, and provided Congress with documents detailing the request that were more than 100 pages long.

The Pentagon’s supplemental request for the $67 billion was seven pages and included only vague references to individual items, the letter said, citing a $1.2 billion request for “administration priorities.”

To make the lawmakers’ point, the letter uses Hegseth’s own statement last year saying American taxpayers deserve to know where their money goes and how it’s spent.

“We agree,” the senators write.