In the middle of his speech on Jan. 21 at the World Economic Forum, Ukrainian President Petro Poroshenko left the podium, walked to the edge of the stage and took a large hunk of metal from a man in the audience. It was a shrapnel-scarred panel from a public bus, Poroshenko explained, that was hit by a rocket on Jan. 13 near the Ukrainian town of Volnovakha, killing 13 of its passengers and wounding more than a dozen others.