  Unscreened electrostatic interactions exert a profound effect on the onset of
the buckling instability of a charged rod. When this interaction is unscreened,
the threshold value of the compressional force needed to induce buckling is
independent of rod length for sufficiently long rods. In the case of rods of
intermediate length, the critical buckling force crosses over from the classic
inverse-square length dependence to asymptotic length-independent form with
increasing rod length. It is suggested that this effect might lead to the
possibility of the ``electromechanical'' stiffening of nanotubes, which would
allow relatively long segments of them to be used as atomic force probes.
