Hegseth told lawmakers the Trump administration needs nearly twice the amount already spent to continue operations in the coming months.
In an interview with Bloomberg he believes even that estimate is low. But either way, he said the amount is dangerously high.
"No one in the history of the country has ever asked for this much money. This is more money that you can't even print that fast," he said. "So it threatens our country. The biggest threat we have right now is our debt. We are more in danger of devaluing our currency than we are of Iran invading the United States."
The senator described the ask as "completely and utterly fiscally irresponsible."
News outlets have reported internal costs at the Department of Defense could actually be as high as 80 to 100 billion so far as the U.S. works to repair damaged military bases, replace destroyed aircraft and replenish weaponry.
Hegseth has acknowledged Iran still has "capabilities" but maintains that U.S. operations in the region have put the country in "the worst place it's ever been."