Air force officials and Boeing engineers have started the years-long process of replacing Air Force One, the legendary aircraft that whisks the American president and his entourage around the world.

The Pentagon last week approved the first of a series of contracts with Boeing, the US aerospace giant chosen to convert a pair of its 747-8 jumbo jets — there are actually two Air Force Ones — into state-of-the-art, luxury command centers.

That first contract, worth a relatively small $25.7 million, is for Boeing to look for cost savings and get a better sense of the scope of the massive task at hand, the Air Force said.

Air Force One is an instantly recognizable emblem of American power.