Defense Secretary Leon Panetta formally notified Congress on Wednesday that the Pentagon plans to put civilian defense employees on unpaid leave this year if $46 billion in across-the-board U.S. government spending cuts take effect on March 1.

The announcement of congressional notification begins a 45-day process that could ultimately lead to 22 days of unpaid leave for most of the department’s 800,000 civilian employees around the globe.

In a letter released by House of Representatives Speaker John Boehner, Panetta said the furloughs would be “disruptive and damaging” to the Pentagon’s defense mission, but there were no “viable alternatives” to reduce spending if the budget cuts occur.

President Barack Obama has been sounding the alarm about the impact of the $85 billion in automatic across-the-board government spending cuts due to take effect starting next month. The president turned to local television stations across the country on Wednesday to increase public pressure on congressional Republicans to avert the cuts.

In addition, Secretary of State John Kerry defended U.S. foreign affairs spending against the backdrop of looming cuts, saying it protects U.S. security and creates jobs.

“Foreign assistance is not a giveaway. It’s not charity. It is an investment in a strong America and in a free world,” Kerry said at the University of Virginia.

An administration official, who asked not to be named, said that even White House operations will be not spared under the cuts.

Pentagon Comptroller Robert Hale said there would be “very limited exceptions” to the furloughs, including civilians in combat zones, foreign civilians at overseas bases, some police and healthcare workers and political appointees exempted by law.

Hale declined to estimate what percentage of the civilian workers were likely to be furloughed but said it would be more than half. Another defense official said, “we expect more than 80 percent to be furloughed.”