The RC-135 has 14 variants which include:
RC-135A,
RC-135B,
RC-135C Big Team,
RC-135D Rivet Brass,
RC-135E Rivet Amber,
RC-135M Rivet Card,
RC-135S Rivet Ball,
RC-135S Cobra Ball,
RC-135T Rivet Dandy,
RC-135T Trainer Configuration,
RC-135U Combat Sent,
RC-135V/W Rivet Joint,
RC-135X Cobra Eye,
RC-135W Air Seeker.
.
I would expect that the balloon would have been "examined" by several of these RC-135 variants as it floated across the U.S.
The have been several flybys in the past 10 minutes by US surveillance planes on the live video.
F22s circling apparently.