Jennifer Whitlow, the top corporate spokeswoman at Lockheed Martin [LMT] for the past six years, is resigning to become Chief Communications Officer for UnitedHealth Group [UNH].

Andrea Greenan, the vice president for internal communication, will replace her on an interim basis while Lockheed Martin searches for a full-time replacement. In her new job, Whitlow will be based in Minneapolis. Her last day at Lockheed Martin will be March 29.

Whitlow worked at Pratt & Whitney and United Technologies [UTX] before moving to Lockheed Martin in 2010. She had been widely expected to stay in the role until CEO Marillyn Hewson retires. Although the succession plan for Hewson is not clear, many expect her to go in the next 18 months or so.

Whitlow’s exit marks the latest in a series of communication shakeups across the top defense contractors. Boeing‘s [BA] top spokesman resigned in 2018 after a short tenure. That slot was recently filled by long-time company employee Anne Toulouse. Lucy Ryan jumped from the top communications job at General Dynamics [GD] to Northrop Grumman [NOC] also in 2018.

Note: Story was updated March 28.