Senior officials acknowledge that powerful constituencies are expected to line up in opposition to cuts of favorite programs  with criticism anticipated from the defense industry, Congress, military headquarters, Pentagon personnel and retirees.

“We will need to address the reasons things are in the budget in order to be able to reduce overhead,” Mr. Lynn said. “We are going to have to be engaged in dialogue with industry, with Congress, with other agencies, with the White House and inside the Pentagon  all the stakeholders.”

The new directives are aimed at three distinct areas of spending.

The first is management and personnel, overhead, logistics and base operations, and support missions.

The second is the war-fighting accounts themselves. Major targets for the next fiscal year already identified by the Pentagon leadership, and supported by the White House, include canceling a program to buy an alternative engine for the F-35 warplane and ending production of the C-17 cargo aircraft. Officials said a range of lower-priority programs would also be under review.

The third area is Mr. Gates’s own Defense Department staff and agencies.

Pentagon agencies that handle specialized tasks like missile defense and commissaries, as well as Mr. Gates’s directorates for such matters as personnel and readiness, policy, intelligence and public affairs, will be ordered to reduce costs by trimming personnel and streamlining business practices.

Mr. Gates set a deadline of July 31 for receiving details on programs and personnel to be cut and a description of savings in management practices to be included in the budget proposal for the next fiscal year, 2012. Two-thirds of the ordered savings must be an actual money transfer from noncombat accounts to the war-fighting budget, while one-third can be found in efficiencies and eliminating redundancies and overhead.

The specific instructions are included in three unclassified guidance documents signed by Mr. Gates  one to the armed services, one to the Pentagon’s primary agencies and directorates, and one to the global combatant commands.