Six years ago, a panel led by Donald Rumsfeld warned about the possibility of a "space Pearl Harbor.".

Six years ago, a panel led by Donald Rumsfeld warned about the possibility of a "space Pearl Harbor." On January 11, we caught a glimpse of what such a disaster might look like, when China destroyed an aging weather satellite with a ground-based missile. China's development of anti-satellite technology is a provocative threat to U.S. military supremacy, which relies heavily on space-based assets for communications, navigation, and surveillance. Locked into predictable orbits, these satellites are vulnerable to rivals who achieve a minimal competence in rocketry. Liberals tend to look to arms-control treaties for salvation, but these pacts are more likely to prevent the United States from designing effective countermeasures than to halt Chinese ambitions. If we want to protect future generations of national-security satellites, they will need to be maneuverable, rapidly replaceable, and able to take defensive actions. It may also become necessary to develop space-based weapons. The alternative is practically to invite a new day of infamy.