They are now sending voice, images and other data over the Skynet 5A platform. The spacecraft, which was launched in March, is part of a £3.6bn project to upgrade the super-fast connections between command centres.Click here to see how the system will be deployed
"It's making a clear difference already," Brigadier Simon Shadbolt at the Ministry of Defence told BBC News. "In Afghanistan, where we've been using the system probably more than in Iraq, our troops have seen a noticeable increase in capability."
Skynet 5A was launched from Kourou in French Guiana on 11 March.