Jeff Bezos' Blue Origin is frustrating one of its closest partners with rocket-engine delays, according to a report

• United Launch Alliance is said to be frustrated with Blue Origin over delays to rocket engines.
• Jeff Bezos' Blue Origin is building two rocket engines for ULA's Vulcan rocket.
• With a planned rocket launch delayed to 2022, sources expressed concerns to Ars Technica.

Blue Origin's relationship with one of its closest partners, United Launch Alliance, has soured over delays to rocket engines, according to a new Ars Technica report.

Blue Origin, Jeff Bezos' aerospace company, is building two engines for ULA's Vulcan rocket. ULA wanted to launch the rocket into space this year, but the engines have been delayed, Ars reported. The Vulcan rocket is a two-stage launch vehicle that is set to send satellites into orbit for the US Space Force.

"There is great concern about this engine development," one industry source told Ars. "There is great concern that Blue is not putting enough attention and priority on the engine."

The source added that ULA CEO Tory Bruno wasn't showing the full extent of his concern to the public.

"He's protecting Blue Origin," a second industry source told Ars, commenting on Bruno's lack of public criticism of the engine delay. "It does no good to throw Blue Origin under the bus."

Bruno had previously said he expected the rocket to launch in 2021. But he told Aviation Week in June that the first launch had been nudged back to 2022.

Blue Origin and ULA back in 2014 announced their partnership to fund the development of the new BE-4 rocket engines.

A third industry source told Ars that ULA might not be happy with the way its collaboration with Blue Origin worked out but for the time being had "no recourse but to make the marriage with Blue Origin work."

The sources told Ars that Space Force officials were also annoyed about the delay because they wanted to start flying the rocket. The tension, they said, had put pressure on Blue Origin engineers.

ULA and Blue Origin did not immediately respond to requests for comment from Insider.

ULA declined to comment to Ars on when Blue Origin's rocket engines were expected to be finished. It also declined to comment to Ars on any fallout with Bezos' company.

Industry sources told Ars that ULA chose Blue Origin's engine over one designed by Aerojet Rocketdyne but was unlikely to reconsider Aerojet's engines.