Situation:
Spring Move
Russia
F Bla
A Con
A Arm

Turkey
F Smy
A Ank

All neighboring spaces are empty and will remain so.

Seems like best Russian move vs. all possible defenses is:
A Arm - Ank
F Bla S A Arm-Ank
A Con S A Arm-Ank

This destroys the army in Ank vs. any defense except
A Ank-Con
F Smy S A Ank-Con.

Even in that case, A Arm-Ank succeeds, A Con retreats to Bul and the next turn F Bla supported by both armies wins. So Russia is guaranteed to conquer turkey in 3 turns.

The other viable attack
A Con-Ank
A Arm S A Con-Ank
F Bla S A Con-Ank

Wins vs. the A Ank-Con defense and conquers turkey in 2 turns but loses (badly) to
A Ank S F Smy-Con
F Smy - Con

which is actually a better position for Turkey than the start!

Should Russia always then move A Arm-Ank with 2 supports (in which case should Turkey always move A Ank-Con with support, which fails vs. all other attacks) or should he randomize in some way?