In a written message to employees, Panetta said that he notified members of Congress Wednesday that if the White House and Congress cannot strike a deficit reduction deal before March 1 to avoid the furloughs, all affected workers will get at least 30 days' advance notice.

The furloughs would be part of broad spending cuts the Pentagon would implement in order to achieve $46 billion in reductions through the end of this budget year, which ends Sept. 30. More cuts would come in future years as long as the automatic government spending cuts, known as sequestration, remained in effect.

"In the event of sequestration we will do everything we can to be able to continue to perform our core mission of providing for the security of the United States, but there is no mistaking that the rigid nature of the cuts forced upon this department, and their scale, will result in a serious erosion of readiness across the force," Panetta wrote.