The Northrop Grumman B-21 Raider is an American strategic bomber under development for the United States Air Force (USAF) by Northrop Grumman. As part of the Long Range Strike Bomber (LRS-B) program, it is to be a long-range, stealth intercontinental strategic bomber for the USAF, able to deliver conventional and thermonuclear weapons. The Air Force intends the B-21 to replace the Rockwell B-1 Lancer and Northrop Grumman B-2 Spirit by 2040, and possibly the Boeing B-52 Stratofortress after that.