Congress and the White House have until March 1 to agree on a new spending plan or automatic, across the board spending cuts of $500 billion from the federal budget over 10 years will become law.
Automatic spending cuts, known as sequestration, would result in furloughs affecting "a vast majority" of the department's civilian personnel, Panetta said. He also said it would result in "severe damage ... both to this department and to our national defense."
Stars and Stripes reported Wednesday that the plan is to place about 800,000 civilian personnel on furlough one day per week for 22 weeks, starting in late April and running through the fiscal year, which ends on Sept. 30.
The few exceptions include jobs that protect either life or property but even first responder personnel aren't entirely exempt, the newspaper said.
"That doesn't mean a wholesale protection of those jobs. They can still do minimum manning," said Pentagon spokeswoman U.S. Army Lt. Col. Elizabeth Robbins.
Over the course of the year, the furloughs would result in a one-month loss of pay for those affected. Unlike previous department furloughs, there are no plans to make up that loss to the workers affected, Stars and Stripes reported.
Panetta further lamented the spending cuts in a news release: "Our most important asset at the department is our world-class personnel. You are fighting every day to keep our country strong and secure, and rest assured that the leaders of this department will continue to fight with you and for you."