Masked Russian troops have moved into Crimea, with unmarked uniforms and heavy arms. Some of the residents cheer them, while others fear them. And they may be the undoing of the delicate ethnic balance in Crimea.Masked Russian troops have moved into Crimea, with unmarked uniforms and heavy arms. Some of the residents cheer them, while others fear them. And they may be the undoing of the delicate ethnic balance in Crimea.