Secret US satellite Zuma, which was launched by Elon Musk's Space X, has crashed into the Indian ocean. (See: SpaceX launches US government's Zuma spacecraft into orbit)
Elon Musks's private space agency said its Falcon 9 rocket operated ''correctly'' despite the loss of the top secret mission.
SpaceX president Gwynn Shotwell said, ''For clarity: 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. Information published that is contrary to this statement is categorically false. Due to the classified nature of the payload, no further comment is possible."
A US official confirmed that the satellite crashed down to earth somewhere in the Indian Ocean.
According to reports, the ''secret spy satellite'' failed to maintain its orbit after detaching from SpaceX's rocket.
Northrop Grumman Corp, which built the billion-dollar satellite, offered only a cryptic comment through a spokesman in view of the classified nature of the mission.
He said, ''This is a classified mission. We cannot comment on classified missions.''
SpaceX said in response to request for comment, ''We do not comment on missions of this nature, but as of right now reviews of the data indicate Falcon 9 performed nominally.''
The Wall Street Journal quoted unidentified congressional officials who were briefed on the mission as saying the satellite apparently did not separate from the second stage, and plunged through the atmosphere and burned up.
Harvard astronomer Jonathan McDowell, who catalogues launches worldwide, said an object the size of a second stage re-entered earth's atmosphere over Sudan some two hours after the launch, AP reported.
He added a number designation was assigned by federal space trackers, but that doesn't mean there is anything still in orbit.