(Reuters) -Boeing has hired a former Northrop Grumman executive, Steve Sullivan, to lead its Air Force One program, according to two people briefed on the matter.

Sullivan, who previously worked on key Northrop programs including the B-21 bomber, replaces Gregg Coffey, who is moving to another role at the U.S. planemaker.

Boeing did not immediately respond to a Reuters request for a comment.

The Air Force One program, which involves converting two 747-8 aircraft into VC-25B jets equipped with advanced communications and defense systems to serve as the next generation of U.S. presidential air transport, has faced chronic delays over the last decade.

Delivery of the two new 747-8s is three years behind schedule and now expected in 2027.

The news of the appointment comes after the U.S. military in May accepted a 747 jetliner as a gift from Qatar. The Air Force was tasked with evaluating options to quickly upgrade it for presidential use.

(Reporting by Nathan Gomes and Mike Stone; Editing by Shinjini Ganguli)