The U.S. Air Force is seeking a manufacturer to develop a new long-range strike bomber (LRS-B) by next spring.

The service issued a request for proposal for the bomber on Wednesday in what will be a multibillion-dollar program.

The Air Force “expects to field 80 to 100 of the bombers to replace the aging B-52 Stratofortress and B-2 Spirit fleets,” the Air Force Times reported.

“The LRS-B is a top modernization priority for the Air Force,” Air Force Secretary Deborah Lee James said in the statement. “It will be an adaptable and highly capable system based upon mature technology. We look forward to industry’s best efforts in supporting this critical national security capability.”

Reuters reported:

The competition is expected to pit Northrop Grumman Corp , the maker of the B-2 bomber, against a combined team of Boeing Co and Lockheed Martin Corp, the two top weapons makers for the U.S. government.

The Air Force has not released a specific decision date on the RFP.