Tear gas is banned in international warfare, and its health risks are well-documented. Still, it remains a crowd-control agent of choice for police worldwide.

The Quad, composed of the United States, Australia, India, and Japan, is not a formal alliance. Still, the group has intensified its security and economic ties as tensions with China rise.

The Chinese government’s increasingly aggressive diplomacy has hurt its image in much of the world. It’s unlikely to improve anytime soon.

The CDC and other U.S. agencies are working to stop the spread of a new coronavirus that originated in China. But public health resources could become stretched if the outbreak worsens.