WASHINGTON, Oct 5: China has beamed a ground-based laser at US spy satellites over its territory, a US agency said, in an action that exposed the potential vulnerability of space systems that provide crucial data to American troops and consumers around the world.

The Defence Department remains tight-lipped about details, including which satellite was involved or when it occurred.

The Pentagon’s National Reconnaissance Office Director Donald Kerr last week acknowledged the incident, first reported by Defence News, but said it did not materially damage the US satellite’s ability to collect information.

“It makes us think,” Mr Kerr told reporters.

The issue looms large, given that US military operations have rapidly grown more reliant on satellite data for everything from targeting bombs to relaying communications to spying on enemy nations.

Critical US space assets include a constellation of 30 Global Positioning Satellites that help target bombs and find enemy locations. This system is also widely used in commercial applications, ranging from car navigation systems to automatic teller machines.

The Pentagon also depends on communications satellites that relay sensitive messages to battlefield commanders, and satellites that track weather in critical areas so US troops can plan their missions.

“Space is a much bigger part of our military posture than it used to be, so any effort by the Chinese or anybody else to jam our satellites is potentially a big deal,” said Loren Thompson, defence analyst with the Virginia-based Lexington Institute.

FRESH CONCERNS: Clearly, the incident sparked fresh concerns among US officials and watchdog groups about the US ability to determine if satellite problems are caused by malfunctions, weather anomalies like solar flares, or targeted attacks.