McLean-based Sotera Defense Solutions said Thursday that John Hillen will step down as the company’s chief executive and become vice chairman of the company’s advisory board.

The contractor’s board has begun searching for a new CEO, according to the announcement.

Hillen has run Sotera since 2008, including taking the company public in 2009 and selling it to a private-equity firm in 2011. (The company was previously known as Global Defense Technology & Systems.)

Though Hillen has spent many years in government contracting, he also served in government as assistant secretary of state for political-military affairs from 2005 to 2007 and was also an Army officer.

He declined to comment beyond the press release.

Sotera said in the interim it will be led by William Cave, who is executive vice president and general manager of the company’s defense and intelligence solutions unit, and Laurie Villano, executive vice president of Sotera’s cyber systems and solutions business.