Boeing has rejected an offer by Aerojet Rocketdyne Holdings, Inc. to buy the United Launch Alliance, the company's top official announced on Wednesday.

Aerojet Rocketdyne offered Boeing $2 billion to acquire ULA. The launch service company was formed in 2006 as a joint venture between Boeing and Lockeed Martin, with both companies splitting the profits evenly. It provides spacecraft launch services for the U.S. Department of Defense, NASA and other organizations.

ULA announced it was undergoing significant restructuring in 2014 in an effort to bring the costs of launch operations down. Experts speculate a hypothetical purchase of ULA by Aerojet Rocketdyne would shake up the global rocket marketplace, an industry feeling increasing pressure as more private forces like Elon Musk's SpaceX and Jeff Bezos' Blue Origin aim to offer low-cost launches.

However, Boeing is showing no willingness to let go of ULA.

"[ULA will be] a huge part of our portfolio going forward," Boeing Defense, Space & Security president Chris Chadwick told Defense News. "This bid, we've really not spent much time on it at all, because we're focusing in a totally different direction," he said.

Aerojet Rocketdyne's offer was pending for several weeks, as the company hoped to make the big announcement during this week's AFA Air and Space Conference.