Turkish President Recep Tayyip Erdogan and Russian President Vladimir Putin have been well aware that competition between their countries has been growing on multiple fronts. And until Tuesday, when Turkish F-16s downed a Russian Su-24 near the Syrian border, both took great care to avoid having that competition devolve into outright confrontation. A number of factors will drive Moscow and Ankara to try to temper the latest bout of hostilities, but neither Putin nor Erdogan will be able to avoid the uncomfortable reality that geopolitical forces are once again pulling these old rivals further apart....