Sandra Erwin, for SpaceNews:
Rogers and Cooper also want more information on what the Air Force is doing to develop launch vehicle upper stages to be used for the defense of U.S. space assets. “Advanced upper stages could increase the operational flexibility and on-orbit reusability of the holistic launch system while also allowing for greater delivery of mass to orbit,” says the bill. It asks the Air Force to provide a briefing on “next generation upper stage technology.”
This language is surely the byproduct of ULA lobbying for funding that can be used for Centaur V and ACES, but I would absolutely support a program focused on upper stages.
That said, I would be very disappointed if the definition of “upper stages” was limited to traditional stages like Centaur and not inclusive of things that push the future forward, like SpaceX’s BFS.