What do the Turks think they're doing. Intercepting a civil aircraft of another country not at war with them. This is terrorism, or whatelse would you call a hijack like this?
Because the weapons that the 320 was carrying could in theory be used against Turkey. If someone was to lob a bomb into your back garden you wouldn't take too kindly to it.
Just out of curiosity, but why would this be any different from the Russian ship, suspected of carrying helicopters, that recently got turned away from sailing to Syria by the British navy?
Apart from China and Russia, the rest of the world don't want to re-arm the Assad regime and prolong the civil war.