France’s defence ministry announced on Thursday the purchase of 12 Airbus refueling tankers worth around €3 billion ($3.8 billion).

“Our desire to modernize our airborne deterrence division is taking concrete form with this contract,” said Defence Minister Jean-Yves Le Drian in a statement.

The first two Airbus A330 MRTT planes are to be delivered in 2018 and 2019, with one or two more planes added each year after that.

They will gradually replace the air force’s aging fleet of Boeing KC-135 planes, some of which are more than 50 years old.