Lockheed Martin’s District-based Mission Systems and Training unit will cut about 600 employees nationally to adjust to increased competition and uncertain funding, a company spokesman said Wednesday.

The spokesman said Lockheed will notify affected employees Nov. 6, but he expects the number affected locally to be fewer than 20.

The Bethesda-based contracting giant has been regularly trimming its payroll as government spending declines. A company spokesman said Wednesday that while the federal government shutdown has affected its business, these cuts are “independent from that event.”

The mission systems unit was created last year when Lockheed split its electronic systems business — previously headed by Marillyn A. Hewson, now Lockheed’s chief executive — into two parts: Mission Systems and Training and the Dallas-based Missiles and Fire Control.

Mission Systems and Training, which is based near the Navy Yard, has about 16,000 employees and has been rapidly increasing its focus on drones and other unmanned systems, including making three acquisitions last year.

The group bought almost all the assets of CDL Systems, which produces software used in drones, as well as Chandler/May, which specializes in ground control stations, and Procerus, which focuses on auto­pilot and other avionics for micro unmanned aerial systems.