Testifying before the Senate Appropriations Committee, Hegseth told lawmakers the figure includes both current operational costs and projected expenses through the end of the fiscal year on Sept. 30.

"Some of that number captures additional O&M, military pay and other costs that would be anticipated through the fiscal year," Hegseth told Sen. Dick Durbin.

"So some of that anticipates what costs would be going out in the future as well."

Durbin pressed Hegseth to clarify the figure.

"So the new number you've given me is what?" the Illinois Democrat asked.

"$37.5 billion," Hegseth replied.

Durbin followed up by asking what period the estimate covers.

"Through what period of time?"

"Through now for certain aspects of it, but also military pay, O&M and other anticipated costs through Sept. 30, Senator," Hegseth replied.