Pentagon officials told US lawmakers in a closed-door briefing on Capitol Hill on Tuesday that they estimated the cost of the war against Iran to exceed $11.3 billion in the first six days alone, according to three people familiar with the briefing.The estimate did not include many costs associated with the operation, such as the build-up of military hardware and personnel before the first attacks. For this reason, lawmakers expect that number to increase significantly as the Pentagon continues to calculate the costs accrued in the first week.Still, it appears to be the most comprehensive assessment yet received by Congress amid growing questions about the war’s objectives, scope, and timeline. The New York Times and The Washington Post previously reported that defense officials said in a recent congressional briefing that the military had used $5.6 billion worth of munitions in the first two days of the war.This is far greater than the publicly reported quantity and rate of munitions being burned. The Center for Strategic and International Studies estimated that the cost of the first 100 hours of operation was $3.7 billion, or $891.4 million each day.The first wave of bombings used weapons including AGM-154 glide bombs, which can cost $578,000 to $836,000. The Navy bought 3,000 of them about two decades ago. Since then, the US military has said it will begin using much less expensive bombs such as the Joint Direct Attack Munition. The smallest size weapon costs about $1,000, and the guidance kit costs about $38,000.Some Republicans – including Senator Mitch McConnell of Kentucky, chairman of the subcommittee that funds the Pentagon – have urged during several administrations that the United States increase its spending on munitions production.But other Republicans have been hesitant to increase military funding and in recent days have questioned the idea of approving costly supplemental funding for a conflict they worry it could open. And Democrats have expressed considerable skepticism about his willingness to support an emergency funding measure for the operation.