A new analysis has revealed that the United States spent about $3.7bn during the first 100 hours of its military campaign against Iran, highlighting how expensive the early phase of the conflict has been.

The estimate was presented by the Washington based think tank Center for Strategic and International Studies. Researchers said the war has been costing nearly $891.4m every day during its opening stage.

Experts explained that most of the spending comes from the use of advanced weapons and expensive missiles during the initial attacks. In the early phase of air campaigns, militaries usually rely on high tech and costly munitions to hit important targets quickly.

According to the report, US forces used more than 2,000 different types of munitions during the first 100 hours of the campaign. Replacing these weapons alone could cost around $3.1bn, making it the largest part of the overall expense.

The report also revealed that most of the spending was not included in the Pentagon’s original defence budget. Around $3.5bn of the total cost was unplanned, which means the US Department of Defense may soon need to ask Congress for additional funding to continue the operation.

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Analysts believe the total cost of the war could rise significantly if the conflict continues for several weeks. US officials have already indicated that the military campaign may expand, which would increase the financial burden even further.

Apart from financial costs, the conflict is also causing political debate in the United States. Rising war expenses and concerns about inflation and fuel prices may affect public support for the military operation.

Wars often become very expensive in the early days because advanced weapons are used quickly. If the conflict continues, the cost may rise even faster. This could create political pressure inside the United States and increase debate about the war.