WASHINGTON — An award for the U.S. Air Force’s Ground Based Strategic Deterrent program is slated to be granted by the end of September, but it could happen earlier, the service’s acquisition executive said Thursday.

“I think early award is possible on GBSD,” Will Roper told reporters during a teleconference. “I’m very hopeful, but because GBSD has a large component of classified work, that team is having to go in and maintain workforce in our [sensitive compartmented information facilities] and in our classified spaces. So we’re watching very carefully to make sure the installations are open to allow that work.”

As the sole bidder on the GBSD program, Northrop Grumman is anticipated to win an estimated $85 billion to design and build the Air Force’s next-generation intercontinental ballistic missiles.

Northrop and Boeing each were awarded contracts in 2017 for the technology-maturation and risk-reduction phase of the program, and Roper confirmed Thursday that Northrop continues work under that contract.

However, Boeing declined to move forward in the competition due to what it perceived as an unfair advantage in Northrop’s purchase of Orbital ATK — now Northrop Grumman Innovation Systems — which is one of only two solid-fuel rocket motor manufacturers in the United States.

GBSD is set to replace the Minuteman III ICBMs in the mid 2020s. The Pentagon’s top acquisition official, Ellen Lord, has said there is “no margin” to do another service life extension for the Minuteman III, which was fielded in the 1960s and has gone through only minimal upgrades over its 50 years of use.

Roper is pleased with the progress Northrop is making on GBSD so far, particularly its use of high-fidelity models that can simulate the assembly, performance and maintenance of the system.

Modernizing the United States’ nuclear triad — its ICBMs, bombers and ballistic missile submarines — has been the military’s top acquisition for almost a decade. But while Roper acknowledged that the Defense Department’s top-line budget could remain stagnant or even decrease in the aftermath of the new coronavirus pandemic, he doesn’t expect it to have an impact on nuclear modernization.

“As the budget comes down, there will be more tough choices ahead,” he said. “My worry — concern — is less about any program in the nuclear triad. It’s more outside of that: Where would we find that billpayer?”