SPY satellites have a new role: as well as watching us they are now spying on each other.

The Pentagon admitted last week that it is using two covert inspection satellites developed for the Defense Advanced Research Projects Agency to assess damage to a failed geostationary satellite – something no one suspected the US could do. If such satellites can get that close to a target, they could probably attack it.

The Department of Defense says its Mitex micro-satellites, which were launched in 2006, have been jetting around the geostationary ring and have now jointly inspected DSP 23, which was …