The warning may or may not be real, but Russian state media say Ukraine must surrender Crimea tomorrow or face a "military storm." Russian troops have crossed the border, and it's not clear how far President Putin wants to go. Meantime, Ukraine's new government is asking support from the West. As President Obama considers his options in the middle of Europe, the issue's a game-changer for the humanitarian disaster in Syria, which is getting worse by the day We look at two international crisis points, where the US and Russia have critical roles to play.
Banner image: Military personnel, believed to be Russian servicemen, walk outside the territory of a Ukrainian military unit in the village of Perevalnoye outside Simferopol March 3, 2014. Photo: Baz Ratner/Reuters