BRUSSELS (AP) — NATO and U.S. aircraft-maker Boeing have agreed to sign a $1 billion contract to refurbish the military alliance’s aging fleet of surveillance planes, so they can continue to serve as the organization’s eye in the sky until 2035.

Purchased in 1977 at the height of the Cold War, when Jimmy Carter became U.S. president, the 14 Boeing E-3A planes cost almost $8 billion. The new contract is for their fourth and final upgrade.

NATO Secretary-General Jens Stoltenberg said Wednesday that “the modernization will ensure NATO remains at the leading edge of technology.”

He said it will provide the Airborne Early Warning and Control planes “with sophisticated new communications and networking capabilities so these aircraft can continue their vital mission and contribute to our security.”