Asked to comment, Hawthorne-based SpaceX issued a statement Monday afternoon: "We do not comment on missions of this nature; but as of right now reviews of the data indicate Falcon 9 performed nominally."
A spokesman for Northrop Grumman Corp., which built the satellite estimated to be worth more than $1 billion, said: "This is a classified mission. We cannot comment on classified missions."
The secret satellite, called Zuma, was built for the U.S. government, although it is unclear which part of it. It was supposed to separate after the firing of the second stage of a Falcon 9 rocket. The Journal cited government and industry officials who were briefed on the mission and said the satellite didn't separate and plunged back into the atmosphere.
SpaceX was originally set to launch the Zuma mission in November, but the company tweeted at the time that it was postponing the mission "to take a closer look at data from recent fairing testing for another customer."
SpaceX has been rapidly expanding its launch business, which includes NASA, national security and commercial missions. The company has recently ramped up its launch pace, even launching two missions from opposite coasts within about 48 hours.
SpaceX launched two other national security missions last year -- a satellite for the National Reconnaissance Office in May and the Pentagon's autonomous space plane known as the X-37B in September.
In 2015, SpaceX was certified by the U.S. Air Force to launch national security satellites. That broke up a longtime and lucrative monopoly held by a joint venture between Lockheed Martin Corp. and Boeing Co. known as United Launch Alliance.
On its website, SpaceX says it has more than 70 upcoming missions on its launch manifest that represent more than $10 billion in contracts. In 2017, SpaceX completed 18 launches.
--This article is written by Samantha Masunaga from The Los Angeles Times and was legally licensed via the Tribune Content Agency through the NewsCred publisher network. Please direct all licensing questions to firstname.lastname@example.org.