"Hillary Clinton is campaigning on the creation of no-fly zones in Syria, one of the few big breaks she has made from President Obama while campaigning for the White House." http://thehill.com/policy/defense/304312-clintons-big-difference-with-obama So, no-fly zone means boots on the ground (outside of Syria) to support it. But the real question is: Syria's weak aviation is helped by Russia's. Syria is the sovereign country. What happens if a Russian aircraft enters into the no-fly zone decided by a foreign country with no legal rights to be there?