Last month, I argued in these pages that the Houthis had handed President Donald Trump leverage over China. Here is what it bought.

The Houthis did not close the Bab el Mandeb to the world. They closed it to one country. In July, they declared a blockade of Saudi shipping. In September, they seized the Yemeni port of Mokha. On Sept. 11, after a drone attack, Saudi Arabia shut the pipeline it used to carry oil around the Strait of Hormuz to the Red Sea.