China is giving the U.S. a run for its money. The recent launch of a digital form of the Chinese yuan—bolstered by a disruptive new technology—threatens the dominance of the U.S. dollar and American hegemony. U.S. policy makers should heed the moment and respond with a strengthened form of the dollar in service to the national interest. The greenback is trading at its strongest level since 2002, up more than 10% year-to-date against most major currencies, including the yuan. U.S. authorities, however, shouldn’t misread the dollar’s strength. American output has fallen, just not as far or fast as that of...