The KH-12 Bravos are nuclear-powered. The on board plutonium is designed to survive re-entry. Some kind of protective shroud.
11 seconds sound clip from the G.I. Jane movie soundboard.
You can hear this line at 01:43:37 in the Blu-ray version of the movie.
Quote context
[...]
- Copy, Las Vegas. Copy, Las Vegas. E.T.A approximately one hour, 20 minutes. Over.
- Are we talking the KH family here, sir? The subhunter satellite?
- Go ahead, Lieutenant. Fill us in.
- The plutonium is weapons grade.
- You know the drill, Master Chief.
- Unfortunately, I do. Carry on.
- Understand. Inner door closed and dogged. Mark and start.
- Clear. Okay. Mr. McCool, set up comms.
[...]