The biggest rocket ever to launch from the US West Coast has lifted off from Vandenberg Air Force Base.
The 72m-high Delta IV Heavy was carrying a classified satellite for the National Reconnaissance Office (NRO).
It has previously only operated from Florida, and the launch pad at the Californian base had to be upgraded to handle the giant vehicle.
Flying the Delta from the West Coast allows the largest reconnaissance satellites to be put into polar orbits.
The vehicle is reserved for military and intelligence use, although there has long been discussion about modifying it for a role in human spaceflight.
The Delta IV Heavy features three core boosters strapped side by side. Each has a Pratt and Whitney Rocketdyne-built RS-68 engine. These motors burn a tonne of propellant every second and produce 2,900 kiloNewtons (650,000lbs) of thrust at lift-off. No details of the payload were given.