WASHINGTON – The U.S. Air Force in April rejected a congressional request to consider holding a competition for the launch of a missile warning satellite, saying the contract will go to its incumbent launch services provider, United Launch Alliance.

The geosynchronous-orbiting satellite, the fourth dedicated craft in the Air Force’s Space Based Infrared System constellation, will launch in 2016 under the service’s $11 billion block buy contract with ULA of Denver. That contract, awarded in 2013, includes production of 36 new Atlas 5 and Delta 4 rocket cores and launch services for vehicles purchased as long ago as 1998.

As part of the 2015 National Defense Authorization Act, lawmakers asked the Air Force to consider putting launch of the satellite, known as SBIRS GEO-4 out to bid. Legislators were looking to increase the number of launches to be subject to competition between ULA and newcomer SpaceX, which in June was certified to launch national security satellites.

But in an April 2 letter to congressional defense committees, the Air Force said it was “not practicable” to put the GEO-4 launch up for bid. The letter was labeled For Official Use Only.

“A competitive source selection and contract award cannot be completed in time to support the required launch date needed for the SBIRS constellation,” Christina Greer, an Air Force spokeswoman, said in a June 25 response to questions from SpaceNews.

SpaceX and ULA are expected to compete later this year to launch one of the Air Force’s next-generation GPS satellites. The contract is the first competitive Defense Department launch in over a decade. The Air Force has planned nine competitive launches through 2017, down from 14 two years ago.