No, they're not.
Although, funfact: you can't sue the US government unless they consent to be sued.
(Edited 15 seconds later.)
@previous (B)
Wikipedia isn't really a good source for this information as it can be edited by anyone. Is there a more reliable link?
@previous (A)
Gray v. Bell, 712 F.2d 490, 507 (D.C. Cir. 1983)
@285,455 (A)
Ah yes, the Sovereign immunity page is very unreliable. Lots of competing edits on there.
(Edited 27 seconds later.)
@285,460 (Killer Lettuce !!iNo3FkiZx)
This seems like the work of sK.