A U.S. drone base in a remote part of West Africa has garnered attention for its $100 million construction price tag. But according to new projections from the Air Force, its initial cost will soon be dwarfed by the price of operating the facility — about $30 million a year. By 2024, when the 10-year agreement for use of the base in Agadez, Niger, ends, its construction and operating costs will top a quarter-billion dollars — or around $280 million, to be more precise.

And that’s actually an undercount. The new projections from the Air Force do not include significant additional costs, such as salaries of the personnel stationed at the base or fuel for the aircraft flying out of Agadez. The facility, which is part of the expanded U.S. military footprint in Africa, is now the largest base-building effort ever undertaken by troops in the history of the U.S. Air Force, according to Richard Komurek, a spokesperson for U.S. Air Forces in Europe and Air Forces Africa.

The outpost — officially a new airfield and associated facilities at Nigerien Air Base 201, or AB 201 — was once billed as a $50 million base dedicated to surveillance drones, and it was to be completed in 2016. Now, it’s slated to be a $100 million base for armed MQ-9 Reaper drones which will finally take flight in 2019, though the construction cost is hardly the end of the tab for the facility.

“It’s probably one of the most remote U.S. military airbases ever built,” said Dan Gettinger, co-founder and co-director of the Center for the Study of the Drone at Bard College and the author of a guide to identifying drone bases from satellite imagery. “Most drone bases on the African continent are appendages to larger airports and airfields, but not Agadez. The existing infrastructure is not there. So, the scale of the project is huge.”

Air Force documents submitted to Congress in 2015 note that the U.S. “negotiated an agreement with the government of Niger to allow for the construction of a new runway and all associated pavements, facilities, and infrastructure adjacent to the Niger Armed Force’s Base Aerienne 201 (Airbase 201) south of the city of Agadez.” When the National Defense Authorization Act for fiscal year 2016 was introduced, embedded in it was a $50 million request for the construction of an “airfield and base camp at Agadez, Niger … to support operations in western Africa.”

Reporting by The Intercept found that the true cost of the airfield is double the reported sum — all of it laid out in a September 2016 article on the “$100 Million Drone Base in Africa.” Despite more recent news reports that the price tag of the base has risen to $110 million, Komurek told The Intercept that the total cost of the project has remained roughly the same, topping out at $98.5 million next year.

While the total budget hasn’t changed, the way its costs are divided has. The price of construction jumped from $50 million to $60 million due to “unanticipated effects of the austere conditions and remote location of Agadez,” including the effects of severe weather, according to Komurek. In fact, in a June 2017 letter to Rep. Charlie Dent, then a senior member of the House Appropriations Committee and chair of the Subcommittee on Military Construction, Veterans Affairs, and Related Agencies, the Defense Department justified the $10 million increase by explaining that “poor initial planning and design” led to unforeseen projects, increased costs in acquiring and delivering three aircraft shelters, and a need for new perimeter security measures.

The Agadez base is now the largest “airman-built” project in Air Force history, according to Mark Kinkade of the Air Force Installation and Mission Support Center, eclipsing construction at Al-Dhafra Air Base in the United Arab Emirates, a longtime clandestine outpost from which the U.S. flies drones and fighter aircraft. Prior to that, the record-holder was Phan Rang Air Base in South Vietnam, which had nearly 150 aircraft assigned to it in 1969.