"There’s a baseline schedule, which is on the books," Kendall told reporters. "[B]ut there’s been no breach of that. But with the internal schedule, there’s been a slip of a few months." 

B-21 manufacturer Northrop Grumman told Defense News the program "continues to focus on system maturity, production readiness and sustainment preparedness to best position the B-21 for first flight an effective flight test campaign, leading to initial operating capability." 

MILITARY PILOTS AND GROUND CREWS SHOWING HIGH RATES OF CANCER, PENTAGON STUDY REVEALS

The B-21 Raider was first unveiled to the public in Palmdale, California in early December. It is the first new American bomber aircraft in more than three decades, and almost every aspect of the program is classified. 

At the time, Northrop Grumman said the rollout of the newest nuclear stealth bomber marks the first time the world’s first sixth-generation aircraft would be seen by the public. 

Per The Air Force Times, Kristyn Jones, the department’s interim undersecretary, revealed in a budged briefing last week that the service has six B-21’s in different stages of production at Air Force Plant 42.

Fox News’ Julia Musto contributed to this report.