  Does the remote measurement-disturbance of the quantum state of a system $B$
by measurement on system $A$ entangled with $B$, constitute a real disturbance
-- i.e., an objective alteration -- of $B$ in an operational sense? Employing
information theoretic criteria motivated by operational considerations alone,
we argue that the disturbance in question is real for a subset of steerable
correlations. This result highlights the distinction between quantum
no-signaling and relativistic signal-locality. It furthermore suggests a
natural reason why a convex operational theory should be non-signaling: namely,
to ensure the consistency between the properties of reduced systems and those
of single systems.
