There is nothing more hideous than one military paying for the weapons of its enemy, yet that is exactly what America's soldiers, sailors, and pilots are now doing. They are, inadvertently, financing the tanks, ships, and planes that China's regime is now developing to kill them. Members of America's armed services have, since 2001, been allowed to participate in the Thrift Savings Plan (TSP), a federal government-sponsored long-term retirement and investment program that is akin to a 401(k). Participants in TSP can invest in Chinese companies, including 22 China-only mutual funds. As a practical matter, China's companies are uninvestable—or at...