The U.S. military cannot fight a high-end conflict without a coalition of friends and allies. In order to conduct effective joint operations, all parties must be able to share information rapidly across secure networks. Unfortunately, adversaries such as China and Russia are conducting continuous cyberattacks on critical allied networks, often with significant success. For the U.S. to have confidence in sharing data with allies, those countries must begin now to implement a program of Zero Trust cybersecurity.