NROL-172 is the 13th mission in the NRO's push to modernize its spy satellite network, aiming for faster and more resilient coverage in risky situations.
The satellites were built by SpaceX and Northrop Grumman, but their details are top secret.
After launch, Falcon 9's booster will land on "Of Course I Still Love You," making it its second flight, and this marks SpaceX's 55th Falcon 9 mission just this year!