Early last summer, Chinese and Indian troops clashed in a surprise border battle in the remote Galwan Valley, bashing each other to death with rocks and clubs.

Four months later and more than 1,500 miles away in Mumbai, India, trains shut down and the stock market closed as the power went out in a city of 20 million people. Hospitals had to switch to emergency generators to keep ventilators running amid a coronavirus outbreak that was among India’s worst.

Now, a new study lends weight to the idea that those two events may have been connected — as part of a broad Chinese cyber campaign against India’s power grid, timed to send a message that if India pressed its claims too hard, the lights could go out across the country.