China took the extraordinary step earlier this month of denying visas to a bipartisan American congressional delegation. We were barred from the country for one reason only—our planned visit to Taiwan.

Chinese officials told members of my staff on multiple occasions that if I canceled the trip to Taiwan, I would be granted a visa. This was visa blackmail, designed to stanch the longstanding tradition of robust U.S. congressional engagement with Taiwan, which is especially critical given the executive branch’s self-imposed...