A secret spy satellite has been pinpointed by amateur space watchers - but no one knows exactly what it's up to.
The world's largest rocket blasted off from Cape Canaveral last week, carrying the secret satellite.
The launch's live feed was cut after a few minutes due to the payload's secrecy.
Just days later, an Australian observer spotted the US National Reconnaissance Office (NRO) satellite.
It was located near longitude 104E, over the Strait of Malacca, a stretch between the Malaysian Peninsula and the Indonesian Island of Sumatra.
The blog of Dutch satellite tracker Marco Langbroek helped guide amateur astronomer Paul Camilleri toward the discovery.
The satellite appears to be drifting west, Mr Langbroek wrote.
"My guess (and no more than that) is that it will eventually stop drifting near either 80E (south of Sri Lanka) or perhaps 10 E (over central Africa)," he said.
"The reason for the initial placement near 104E is likely that in this position it is initially well placed for the Pine Gap Joint Defence Facility ground station in central Australia during the initial check-out phase."
There has been speculation that it is a Mentor satellite, which picks up electronic signals from ships, aircraft, ground stations and other satellites.
The signals are processed on board the Mentor satellites, and encrypted before being sent back to authorities in the US.
The NRO is described on its website as a government agency used when the US "needs eyes and ears in critical places where no human can reach - be it over the most rugged terrain or through the most hostile territory".