A Saudi-led airstrike killed dozens of Yemeni children. Could the world have stopped it?

“When you’re hitting a school bus there is a big problem with your target acquisition process,” Stephens said, referring to the way armed forces distinguish between military and civilian targets. There are established rules meant to prevent this sort of tragedy from happening, he said. "Politics can mean that you loosen or tighten these rules, but the frameworks are there and they [the coalition] just have to abide by them and that’s up to them," Stephens added.