Lockheed Martin [LMT] on Monday said that Dale Bennett, the chief of its Rotary and Mission Systems (RMS) segment, will retire at the end of 2019 and will be succeeded by Frank St. John, who currently leads the Missiles and Fire Control (MFC) segment.

St. John will be succeeded at MFC by Scott Greene, who is currently vice president of the Tactical and Strike Missiles business area within MFC. St. John’s and Greene’s appointments are effective as of Aug. 26.

Bennett joined Lockheed Martin in 1981 and has service as president of several segments and business areas in addition to RMS, including the former Mission Systems and Sensors, Global Training and Logistics, and Simulation, Training & Support. He will remain with the company as a strategic adviser on the executive leadership team until the end of the year.

“We appreciate Dale’s leadership and service over his remarkable 40-year career in the military and in industry,” Marillyn Hewson, Lockheed Martin’s chairman, president and CEO, said in a statement. “His broad experience across engineering, business development and strategy made him a uniquely valuable part of our leadership team. We wish him well in his retirement.”

The $14.3 billion RMS segment includes the Sikorsky business unit, the Aegis Combat System, Littoral Combat Ship, anti-submarine warfare work, cyber security solutions, and military training systems.

St. John, 52, has been with the company more than 30 years. He has been executive vice president of MFC for the past 18 months.

The MFC segment posted $8.5 billion in sales in 2018. The segment oversees the company’s work in advanced combat, missile, rocket and energy systems, and provides technical services and logistics support for the U.S. military services and international customers.

Greene, 61, has led the Tactical and Strike Missiles business area since August 2017.

“Frank and Scott are proven leaders who have built impressive records at Lockheed Martin,” Hewson said. “They bring a commitment to excellence and strong customer focus to their respective business areas.” She also said the new appointments demonstrate the company’s succession planning and the well of talent in its executive leadership team.