Lockheed Martin says it plans to reduce its executive ranks by February, a move that comes as the Pentagon pressures defense contractors to cut overhead costs on huge weapons programs.

Directors and vice presidents are being offered financial incentives to leave by Feb. 1 under a voluntary separation program.

The company doesn't say how many employees are expected to leave or how many qualify.

Defense Secretary Robert Gates said last week that defense contractors should cut costs to help the Pentagon save money. Lockheed, based in Bethesda, Md., is the nation's biggest defense firm.