Officials close to the project say the classified satellite may have been destroyed after it launched last Sunday.
But Elon Musk’s SpaceX said the Falon 9 rocket, which was carrying the Zuma satellite, “did everything right”.
The Zuma project is extremely classified and little has been revealed about its mission.
However details are beginning to emerge of a possibly catastrophic error during last weekend’s launch.
SpaceX Chief Operating Officer Gwynne Shotwell said: “After review of all data to date, Falcon 9 did everything correctly on Sunday night. If we or others find otherwise based on further review, we will report it immediately.
“Due to the classified nature of the payload, no further comment is possible.”
He said “no design, operational or other changes are needed” for future launches and a launch planned for three weeks time will take place as scheduled.
This could indicate a problem with the satellite separating from the rocket. This issue might not lie with SpaceX but instead with the branch of the US military using the satellite.
Astronomer Jonathan McDowell explained: “Normally when you buy a rocket launch, you’ve paid for ‘the payload adapter on the rocket final stage pops the satellite off at the end’.
“But on this mission the customer provided its own payload adapter, so separation may be its problem and not SpaceX’s problem.”
In any case, the US Strategic Command, which is responsible or tracking thousands of man-made objects in Earth’s orbit, said it had not begun monitoring any new satellites – indicating a failure.
SpaceX has 30 missions planned for 2018 – nearly double its record of 18 last year.