Since a state of war does not yet exist, the intruder could have been intercepted & either escorted out of Turkish airspace or ordered to land (backed up by a warning burst which is legal).
There must have been radio contact; this is madness on the Turks’ part.
Look at the map....There is a little finger and the Russian plane, if it did violate their air space, past over the little tip. The plane was not flying into Turkey.
The surviving pilot says no warning was given.