While much of the cybersecurity world’s attention is on fending off Russian hacks against Ukraine, American officials are increasingly worried about another growing threat: attacks by China on U.S. soil. If China invades Taiwan, they say, it is likely to unleash a volley of digital strikes against the United States at the same time. Beijing continues to issue bold threats against the island. Most recently, China renewed military drills around the island in response to last week’s meetings in the U.S. between Taiwan’s president and House leaders — a meeting China called a “provocation.” Top lawmakers, the U.S. intelligence community...