Bethesda-based Lockheed Martin has promoted its chief operating officer into a two-person executive office, potentially signaling a successor to Robert J. Stevens, the company’s chairman and chief executive.

The world’s largest defense contractor announced last month that Christopher E. Kubasik, Lockheed’s president and chief operating officer since the start of 2010, will now become part of what the company is calling the executive office of the chairman. The office will include Stevens and Kubasik and make them interchangeable, a move Lockheed said would improve its agility.

Lockheed leadership thought “the ability to respond in a timely manner to our customers and our shareholders and our employees would ultimately be a competitive differentiator,” said Kubasik. “It is very rare that Bob and I are in our headquarters office on the same day.”

He said his broadened responsibilities will include working with Stevens on the company’s strategic direction, meeting with government and congressional officials and engaging with Wall Street.

As chief operating officer, Kubasik has been one of the drivers of the company’s recent efforts to cut costs, which have included consolidating facilities, offering buyouts to executives and divesting businesses. He came to Lockheed in 1999 and was made chief financial officer in 2001; in 2007, he was named executive vice president of the company’s electronic systems unit. Before he joined Lockheed, he was a partner at Ernst & Young.

Loren Thompson, a defense industry consultant at the Lexington Institute, said Kubasik has been a fast riser within Lockheed.

“When you make the top two people interchangeable, it also signals the marketplace that maybe there is a successor to the current top person waiting in the wings,” Thompson said. “Many people have expected for years that Chris Kubasik was being groomed as Bob Stevens’ successor, and this disclosure will not discourage any such rumors.”

Kubasik himself was quick to quash speculation.

“My focus has been and will continue to be on the role that I’m assigned,” he said. “Any decisions beyond that are at the board level and that’s not anything that I worry about or focus on.”

It wouldn’t be the first time the president and chief operating officer took over. Stevens was named to that role in 2000, after his predecessor resigned just six months into the job. Stevens took over the chief executive position in 2004.

Other local defense contractors have made fairly recent executive changes. Northrop Grumman’s Wes Bush was named chief executive and president in January 2010 and added the chairman role in July of this year. He had previously served as president and chief operating officer of the Falls Church-based contractor.

Jay L. Johnson of General Dynamics was named president and chief executive in July 2009; in May of last year, he became chairman and chief executive.