By Bijan Razzaghi 

The US Air Force is likely to retire both the B-1B and B-2 and keep the B-52 in service once the B-21 becomes fully operational. The B-21 Raider remains largely a secret yet it is known to be stealth and have a payload comparable to both the B-1 and B-2.

The B-21 is part of the US Air Forces big 5 to fully modernize its fleet. The big 5 also includes the F-35A, F-22A,KC-46 and T-X program. The US Air Force plans to procure at least 100 B-21s over the next decade. This will give the US Air Force a large fleet of long range stealth bombers that can mitigate the threats posed by operations in A2/AD environments. 

Currently the B-1B uses advanced Jamming to counter enemy SAM radars but the S-300U/V, S-400, HQ-9 and Buk systems currently deployed can still pose a major threat to the B-1B as it lacks all aspect stealth. Currently the B-1B depends on its standoff capabilities to fire AGM-86 missiles from denied airspace. 

The B-21 Raider will solve the gap in long range strike missions in denied airspace that currently only the B-2 can fill. The US Air Force operates 20 B-2s.