THEN MAYBE THEY SHOULD DO SOMETHING ABOUT IT: China Fears Radioactive Fallout From North Korea Blast.

Chinese government agencies said no radiation has been detected thus far but they will continue to test air, water and soil samples in a network of radiation-monitoring stations that has steadily expanded since 2013 and is due to grow by at least two more stations in the next few months.

The slightest risk of a leak is of huge concern, with more than 100 million people living in China’s three northeastern provinces bordering or near North Korea. The Punggye-ri test site, where the blast took place, is less than 50 miles from China’s border. Nuclear blasts produce radioactive forms of elements such as iodine, exposure to which can cause cancer in humans—or even death in extreme cases.

Sunday’s test shook buildings in Chinese cities near the border and could be felt hundreds of miles away. Some people ran into the streets and posted videos of shaking chandeliers in their apartments. Others have since taken to social media to express alarm.

North Korea wouldn’t still exist if China hadn’t intervened in 1950, and Chinese support has helped keep the virulent Kims in power.