"The situation continues to become more and more complex," Votel said, alluding in part to the effects of a Turkish incursion into the town of Afrin in northwestern Syria.
As for how the missiles are entering Yemen, Gen. Votel said: "Iran has a very sophisticated network of doing this. They can move them by components. They can move them by air. They can move them by maritime means. They can move them by land routes to get their stuff in there and then reassemble it and provide it to the Houthis."