Both Russia and China have, or are developing, the ability to hit U.S. targets with conventional warheads mounted on long-range missiles — whether cruise missiles, hypersonic glide vehicles or perhaps intercontinental ballistic missiles. There is growing concern that China could use swarms of small drones, launched from container ships, to hit targets on the U.S. West Coast or Hawaii.

These attacks probably wouldn’t cause catastrophic destruction. But they could disrupt U.S. logistics, communications and mobilization during a conflict — or simply give Moscow or Beijing a way of deterring, or retaliating for, American strikes against Chinese or Russian territory.

The most likely form of homeland attack wouldn’t involve overt violence at all. Cyberattacks against critical infrastructure or financial systems could snarl everyday life and hinder any response to aggression on the other side of the world. The Colonial Pipeline ransomware attack, which caused gas shortages across the East Coast last spring, offered a chilling preview. Imagine a repeat performance, but on a far larger scale in the middle of a major international crisis over Taiwan, Ukraine or the Baltic states.