ULA will switch launches for its Vulcan Centaur rocket because the Dream Chaser space plane is not ready yet. Its next two launches will focus on national security certification.

ULA delays Dream Chaser space plane launch to certify Vulcan Centaur rocket for US military missions

Source: space
Source Link: https://www.space.com/ula-dream-chaser-launch-vulcan-centaur-postpone-national-security