The contact covers launch services for multiple satellites aboard an Atlas 5 rocket in June 2019. The contract value is just over $191 million, the Air Force said.
The award is the first for United Launch Alliance since the Air Force certified rival SpaceX's Falcon 9 rockets for flight and opened bidding for launch contracts in 2015. ULA, which previously had a monopoly on the military's launch business, sat out the Air Force's first solicitation and lost the second. Both were awarded to SpaceX.
A SpaceX official told Reuters it did not expect to win this bidding competition because the mission required a heavy-lift launcher and its Falcon Heavy booster has not yet flown.
"The mission performance required that we bid Falcon Heavy," SpaceX spokesman John Taylor wrote in a email.
"We did submit a bid, but with the knowledge that our first Falcon Heavy flight might occur after the time of the award. Given we have not flown Falcon Heavy, we did not anticipate winning this mission," he said.
SpaceX's Falcon Heavy is expected to debut this year.
Typically, the Air Force awards contracts two years ahead of a launch. Another branch of the Air Force that handles experimental programs bought a Falcon Heavy rocket ride in 2012. That mission is currently targeted to fly early next year, Leon said.
SpaceX also won Falcon 9 contracts to fly a U.S. National Reconnaissance Office spy satellite, which launched in April, and is scheduled to launch the X-37B robotic space plane for the Air Force Rapid Capabilities Office later this year.
SpaceX is preparing for its 39th launch -- and third in nine days -- on Sunday.
(Reporting By Irene Klotz. Editing by Joseph White and David Gregorio)
(This story has not been edited by NDTV staff and is auto-generated from a syndicated feed.)