Outside estimates project the cost is up to tens of billions of dollars more than the Pentagon says.Show Caption

Senate Democrats are pressing federal budget investigators to probe the gap between the Pentagon's stated cost for the Iran war – $29 billion – and outside estimates that peg the cost up to tens of billions of dollars higher.In a letter sent May 27, Sen. Elizabeth Warren, Sen. Jeff Merkley, the top Democrat on the Senate Budget Committee, and Senate Minority Leader Chuck Schumer urged the Congressional Budget Office to "take into consideration the significant divergence between the administration’s public estimates" for the Iran war's cost and outside estimates from media outlets and analysts."We are concerned that the administration has not been fully truthful or transparent in its public accounting of the war’s costs so far," they wrote. Another 17 Democratic senators signed the letter.The Congressional Budget Office (CBO) is a government agency charged with providing nonpartisan analysis and information to lawmakers on the Hill.Rep. Brendan Boyle, the top Democrat on the House Budget Committee, asked the CBO in early March to investigate the cost of the Iran war. The war began in late February with a massive bombing campaign by the United States and Israel.The Pentagon did not immediately respond to a request for comment.How much does the Pentagon say the war has cost?Jules Hurst, the Pentagon's comptroller, told Congress during a May 12 budget hearing that the Iran war cost taxpayers $29 billion, a $4 billion increase from the $25 billion price tag Hurst had given lawmakers two weeks earlier. That total did not include the cost of damage to U.S. military bases and assets from Iran's attacks, which the Pentagon had not yet fully tallied up, according to Hurst.Independent estimates of the cost range from slightly to vastly higher than Hurst's number. Mark Cancian, a senior defense adviser at the Center for Strategic and International Studies, told USA TODAY earlier this month that the cost for the period covered by Hurst's first estimate was likely closer to $32 to $35 billion. An analysis by the American Enterprise Institute also pegged the cost at up to $35 billion, from the start of the war through April 7, when the United States and Iran struck a temporary ceasefire deal.A source familiar with congressional estimates previously told USA TODAY that battle damage could add another $15 billion to the total cost. CBS and CNN, citing anonymous sources, reported last month that the total cost of the war was closer to $50 billion.The military has requested a record $1.5 trillion for its budget next year, and Pentagon officials have said they would submit a supplemental request to Congress for additional funds for the Iran war. Pentagon officials have not said how much more they plan to request, although news reports have put that number at between $80 and $100 billion.The conflict in Iran has not returned to all-out war since the ceasefire began seven weeks ago, even though the U.S. military launched what it called "self-defense" strikes on southern Iran on May 25 and Israel continues to pummel Lebanon in what it has said is a "deepening" operation against Hezbollah, an ally of Iran. Negotiations between the United States and Iran are ongoing over the Strait of Hormuz, a key shipping channel that Iran choked off in retaliation for the war, causing global oil prices to spike.The United States and Israel first launched a joint attack on Iran on Feb. 28. Thirteen American service members and at least 3,000 Iranians have been killed in the war.