The Defense Department is working with congressional committees to obtain additional funding for fiscal year 2015 for operations against the Islamic State in Iraq and Syria (ISIS), though it is unclear at this point how much additional money DoD might need.

Defense Secretary Chuck Hagel told reporters at the Pentagon Friday that the Pentagon has spent about $7 million to $10 million a day from the Overseas Contingency Operations (OCO) fund since operations against ISIS began in June, “and we are going to require additional funding from Congress as we go forward.”Pentagon_anddowntown_

The Pentagon will begin the new fiscal year on Wednesday under a continuing resolution that provides $85.2 billion in OCO funding–more than the $58.6 billion DoD had requested–but the CR expires Dec. 11. Hagel said “we’re working now with the appropriate committees on how we go forward with authorizations and funding.

Army Gen. Martin Dempsey, chairman of the Joint Chiefs of Staff, said during the same press conference that “when we submitted the budget last year… the Joint Chiefs all said we could accomplish the nation’s security needs with that budget with certain assumptions. One of them was that the number of commitments would either level off or come down. And secondly, that we would get some flexibility in the budget to change paid compensation, health care, retire weapons systems and infrastructure.

“Commitments have gone up. The things that we were looking for in terms of flexibility have only very minimally been delivered,” he said. “So if you’re asking me do I assess right now, as we go into the fall review for ’16, that we’re going to have budget problems? Yes.”

The extent of that budgetary problem may depend on whether operations stay at current levels or increase. A team of analysts from the Center for Strategic and Budgetary Assessments projected that operations in Iraq and Syria could total anywhere from $200 million to $1.8 billion a month, or $2.4 billion to $22 billion annually, depending on the level of intensity of the air strikes and the number of American troops on the ground.

The low-intensity scenario closely resembles the current situation–“Assuming a moderate level of air operations and 2,000 deployed ground forces, the costs would likely run between $200 and $320 million per month,” according to the report. “If air operations are conducted at a higher pace and 5,000 ground forces are deployed, the costs would be between $350 and $570 million per month. If operations expand significantly to include the deployment of 25,000 U.S. troops on the ground, as some have recommended, costs would likely reach $1.1 to $1.8 billion per month.”

The estimate costs include the cost per-hour of flying various types of aircraft, money to replace weapons used in operations, all the costs association with maintaining a second carrier strike group in the region, and an estimated $40,000 to $70,000 per month per person for troops on the ground. These figures do not include the costs of any additional humanitarian aid missions or efforts to train and equip rebel groups or foreign militaries.

Regarding the carrier strike group, CSBA wrote, “This analysis assumes that two aircraft carriers will be deployed to the region, with one in the Persian Gulf supporting operations against [ISIS] and one in the Arabian Sea supporting operations in Afghanistan. Because this is one more carrier than the Navy had planned on deploying, it adds a cost of $40 million to $50 million per month for the carrier, its air wing, and the escort and logistics vessels that support it.”

CSBA added that “the total cost to date from mid-June through Sept. 24 is likely between $780 and $930 million. This is less than 0.2 percent of DoD’s FY 2014 budget, and DoD has indicated that it will be able to cover these expenses from existing appropriations.” However, the report added that DoD had planned its FY ’15 budget around only spending $54 billion in Afghanistan–which it will still need to do–leaving the OCO account well short of where it needs to be for the new fiscal year.

Additionally, as Dempsey noted both in the press conference and at a Senate hearing earlier this month, the base budget will likely need some more funding to support the higher OCO spending. The Navy cannot support an additional carrier strike group forward, the special forces community cannot support additional troops deployed, and so on, without additional base budget funding for training, maintenance and more.