UNITED NEWS INTERNATIONAL (UNI) — The U.S. Air Force is preparing to start mothballing its B-2 and B-1B bomber fleets in preparation for its next-generation stealth bomber.

Air Force Secretary Heather Wilson announced on Feb. 12 that the service will begin retiring the B-1B Lancer and B-2 Spirit as soon as it has built enough B-21s.

The B-21 Raider is the Air Force’s next-generation heavy bomber, which is expected to begin entering service in the mid-2020s.

The Air Force ultimately plans to purchase 100 B-21s with a total price tag of $80 billion.

As for the venerable B-52, don’t expect it to stop flying anytime soon, despite its age.

The B-52 first became operational in 1952, and although the B-2 and B-1B are decades younger, faster and present smaller radar targets, the B-52 can carry a lot of weapons and is far cheaper to operate.