A rocket carrying an intelligence-gathering payload for the Pentagon suffered a technical problem after its launch, officials said. But they were confident Saturday that its secretive mission would be performed.

The Atlas V rocket launched Friday morning, hauling a payload from the National Reconnaissance Office, a division of the Department of Defense that builds and operates spy satellites.

The NRO said Friday night that the launch was successful, but the rocket's Centaur upper stage later had a "technical anomaly which resulted in minor performance degradation."

Rick Oborn, an NRO spokesman, said Saturday there was a slight but manageable problem. Officials did not elaborate and have not said exactly what the rocket was carrying or how it would be used.

"We're confident we're going to perform our mission," Oborn said. When asked if replacement launches would be needed, Oborn said: "If you've got something that's working why do you need a replacement?"

According to United Launch Alliance - the new partnership between Lockheed Martin Corp. and Boeing Co. that was responsible for launching the rocket - the payload will monitor the globe "for early warning of potential trouble spots, compliance with international agreements of all kinds, and changing environmental conditions."

Much of the information typically available for launches was being kept secret because of national security concerns.

Oborn referred further questions to United Launch Alliance.

An engineering review to study what went wrong began Friday, said United Launch Alliance spokeswoman Julie C. Andrews.

"It'll be a very thorough review as always," she said. "We're just not going to speculate on what caused the anomaly."

Andrews confirmed there was a problem with the upper stage, but said "I can't discuss the orbit" at the behest of the NRO. She said both the United Launch Alliance and the client, the NRO, consider the launch a success.

The last time an Atlas V launch had a problem was in 1993, Andrews said.

Air Force space center spokesman Joe Davidson declined to comment beyond what the NRO said Friday night.