For the second time in six months, SpaceX will deploy a US military satellite that was sitting in storage, waiting for a slot on United Launch Alliance’s launch schedule.

Space Systems Command, which oversees the military’s launch program, announced Monday that it is reassigning the launch of a Global Positioning System satellite from ULA’s Vulcan rocket to SpaceX’s Falcon 9. This satellite, designated GPS III SV-08 (Space Vehicle-08), will join the Space Force’s fleet of navigation satellites beaming positioning and timing signals for military and civilian users around the world.

The Space Force did the same thing last year, when teams from the military, SpaceX, and Lockheed Martin pulled a GPS satellite out of storage and prepared it for launch on a Falcon 9 rocket in less than five months, instead of waiting for its previously assigned slot with United Launch Alliance. Officials dubbed the exercise a “Rapid Response Trailblazer” that could be replicated to fulfill future military needs.

In exchange for switching the next GPS satellite to launch on a Falcon 9, the Space Force will move a future GPS payload from SpaceX’s Falcon Heavy back to ULA’s Vulcan. That means the next three GPS satellites will fly on Vulcan. The Space Force compensated ULA for losing a GPS launch to last year’s trailblazing SpaceX mission by reallocating another future GPS satellite to Vulcan.