I don't think the B-1 was in service before the mid-1980s but for the early-1980s timeline it could easily be replaced with the USN's A-5 Vigilante.
From memory I think the US has at least one or two aircraft capable of the supersonic strategic bomber role since the 1960s (such as the B-58 Hustler) and the Soviets had the Tu-22 from about the same time
It's entirely possible the USAF might have some B-58 aircraft in storage that they could reactivate for the 1983 timeline (I think they went out of service in 1970)
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