Both drops in troop levels will take place over the next five years, Panetta said.

Because there will be fewer soldiers and Marines to support, the Air Force is being asked to reduce its airlift fleet. The budget also calls for a reduction of six tactical air squadrons as well as one training squadron. Panetta insists that such moves will mean "minimal risk to our dominance of the skies."

The Navy has perhaps the most difficult duty. Panetta and President Obama have both repeatedly said the United States remains committed to the Asia-Pacific region, which it now supports largely through the 7th Fleet.

But the budget calls for retiring seven old cruisers and two small amphibious ships. The Navy also will delay buying a dozen new ships by a year or more to save money in the short term.

The portion of the outline that may trigger the most opposition is a plan aimed at troops' salaries and retired troops' health benefits. Panetta promised full pay raises for fiscal 2013 and 2014, but he said, "We will achieve some cost savings by providing more limited pay raises beginning in 2015."

As for health care, he plans no changes for active duty troops and their families, but "we decided that to help control the growth of health care costs, we are recommending increases in health care fees, co-pays and deductibles for retirees," Panetta said.