Calling Putin a war criminal is diplomacy guaranteed to lead to a poor result and increased tensions

Behind Putin's Combativeness is the need to stay on the wire in an act where there is no end point to step off.  Secretary of State John Kerry is particularly obtuse on this point.  The way to motivate him is to make him look good. For example when Bashar al-Assad crossed Kerry / Obama's red line with chemical weapons it was Putin who forced his client toward the good result of eliminating them to general acclaim, though not from the U.S. press. Calling Putin a war criminal is diplomacy guaranteed to lead to a poor result and increased tensions. Putin's motive in Syria is to keep Russia's only naval base on the Mediterranean safe with a local leader beholden to him. There is no possibility of Putin abandoning his client. But from Bashar's last visit in Moscow its apparent there is little respect for him. Putin could be convinced to contain him in his Shiite Alawite region of Syria, which of course also has the naval base, because of the doubt that he can ever regain and control the Sunni Arab and Kurdish regions. Of course this negotiation would require the U.S. to give up the pipe dream of a unified Syria. This result gives Putin the image in the World's eye of a disciplining parent of an errant child in pursuit of a real peace and saves him from further insulting Sunni Muslims in Russia and other in his sphere of influence.