Ensigns bearing Confederate and neo-Nazi imagery defined the Jan. 6 riot at the U.S. Capitol. But for Vietnamese Americans, it's the sight of a defunct flag — representing a country that ceased to exist nearly a half-century ago — that brought up painful questions about identity, trauma and the legacy of U.S. imperialism. The yellow-and-red-striped banners of the former South Vietnam flew above crowds of rioters all over the Capitol grounds.