 The real "casus belli", according to both Theophanes and the later Syriac sources, was Justinian's attempt to enforce his exclusive jurisdiction over Cyprus, and to move its population to Cyzicus in northwestern Anatolia, contrary to the treaty.Given the enormous advantages secured by the treaty for Byzantium, Justinian's decision has been criticized by Byzantine and modern historians alike.However, the historian Ralph-Johannes Lilie points out that with Abd al-Malik emerging victorious from the civil war, Justinian may have felt it was only a matter of time until the caliph broke the treaty, and resolved to strike first, before Abd al-Malik could consolidate his position further.