There is little doubt aircraft are designed to survive the inconceivable, see the QF32 A380 incident and the DHL A300 at Baghdad, and an accident that has emerged from Syria reinforces that.
This Syrian Arab Airlines A320 YK-AKF was operating from Damascus to Latakia, when a military helicopter clipped and sheered off the upper half of the vertical stabiliser at 12,000ft. How and why the military helicopter was so close is unclear. The vertical stabiliser provides aircraft with directional yaw stability through the longitudinal axis, without which the aircraft would enter an unrecoverable spin.
It is a great credit to the crew that the aircraft returned safely to Damascus, with no injuries on board. The incorporation of split two piece rudders into aircraft design another factor which perhaps allowed the crew enough control to land safely. The military helicopter was reported crashed with no survivors.
AvHerald reports the incident as taking place around one week ago, and as yet no details have emerged over the impact or the control issues the pilots experienced. Considering the murky political situation in Syria at the moment, it may be likely we never know the full circumstances.