WASHINGTON — Defense Secretary Robert Gates said Monday that tough economic times require that he shutter a major command that employs some 5,000 people around Norfolk, Va., and begin to eliminate other jobs throughout the military.

The announcement was the first major step by Gates to find $100 billion in savings in the next five years. Gates says that money is needed elsewhere within the Defense Department to repair a force ravaged by years of war and to prepare troops for the next fight.

The plan prompted swift political pushback from lawmakers fearful that jobs would be lost in their districts.

“At the end of the day, Secretary Gates and his team will have to convince members of this committee that these efforts will not weaken our nation’s defense,” said Rep. Buck McKeon of California, the top Republican on the House Armed Services Committee.

Sen. Mark Warner, a Virginia Democrat, said he could see “no rational basis” for eliminating Norfolk’s Joint Forces Command, which was created in 1999 to improve the services’ ability to work together and find efficiencies.

“In the business world, you sometimes have to spend money in order to save money,” said Warner.

Sen. Jim Webb, a Virginia Democrat who sits on the Senate Armed Services Committee, called the move a “step backward” that “could be harmful to the capabilities of the finest military in the world.”

In a Pentagon press conference, Gates was optimistic that Congress would eventually swing behind his plan despite lawmakers’ control of the budget. He said in the case of Virginia, the state could wind up with additional jobs if the savings found by closing Joint Forces Command enables a boost in shipbuilding.

Gates described his initiative as just the beginning in his hunt for inefficiencies across the Defense Department, which commands a nearly $700 billion annual budget including war spending.

“The department must start setting priorities, making real trade-offs and separating appetites from real requirements,” Gates said.

Gates vowed to review every corner of the budget, including the military’s rising health care costs.

“There are no sacred cows,” Gates said.

In addition to shutting down Joint Forces Command, Gates wants to:

• Trim by 10 percent the budget for contractors who support the Defense Department;

• Freeze the number of employees working for his office, defense agencies and combatant commands for the next three years; and

• Cut at least 50 general and flag officer positions and 150 senior civilian executive positions over the next two years.

Gates declined to say how much money would be saved by shutting down the command, which holds more than 1 million square feet of real estate.