 For the East Romans, faced with the ever-present necessity of having to battle on two fronts — in the east against Persians, Arabs and Turks, in the north against the Slavs and the steppe nomads — knew from personal experience how expensive war is both in money and manpower.The Byzantines were skilled at using diplomacy as a weapon of war.If the Bulgars threatened, subsidies could be given to the Kiev Rus.