The U.S. Air Force is undertaking a comprehensive modernization of its strategic bomber fleet to maintain air superiority amid escalating threats from rivals such as China and Russia, according to a June 18, 2025 report by the Congressional Research Service.

Currently, the Air Force operates three heavy bombers: the B-52H Stratofortress, B-1B Lancer, and B-2 Spirit. These aircraft perform both nuclear and conventional missions and form a critical part of the U.S. nuclear triad alongside intercontinental ballistic missiles and submarine-launched ballistic missiles.

According to the report, the modernization includes upgrades to the B-52H and B-2 Spirit, along with the phased introduction of the next-generation stealth bomber, the B-21 Raider. 

The B-1B, which no longer carries nuclear weapons, is slated for eventual retirement. 

According to the report, the B-52H, first flown in the 1950s, is being upgraded with new Rolls-Royce F130 engines and an advanced radar system to extend its service life into the 2040s. 

The B-2 Spirit, the only bomber capable of delivering the GBU-57 bunker-busting bomb, is undergoing a $7 billion modernization contract but will eventually be replaced by the B-21 Raider. 

Designed to evade modern air defenses and carry nuclear and conventional weapons, the B-21 Raider was initially planned for 100 units, but the Air Force now estimates it may need up to 145, with some experts suggesting 200.

According to reports, B-21 offers extended range, greater payload flexibility, and the ability to integrate with future drone systems for manned-unmanned teaming. 

Unlike the costly, maintenance-heavy B-2, the digitally designed B-21 is built for easier upkeep and rapid software updates, giving it a technological edge.

The Air Force currently operates 19 B-2 bombers stationed at Whiteman AFB in Missouri.