  This paper considers a constrained discrete-time linear system subject to
actuation attacks. The attacks are modelled as false data injections to the
system, such that the total input (control input plus injection) satisfies hard
input constraints. We establish a sufficient condition under which it is not
possible to maintain the states of the system within a compact state constraint
set for all possible realizations of the actuation attack. The developed
condition is a simple function of the spectral radius of the system, the
relative sizes of the input and state constraint sets, and the proportion of
the input constraint set allowed to the attacker.
