Northrop Grumman is working on a variety of upgrades to improve the U.S. Air Force B-2 bomber’s ability to deliver a variety of weapons.

Though the 30,000-lb. Massive Ordnance Penetrator (MOP) has been integrated onto the stealthy bomber, work is under way to field an upgraded version of the bunker buster, says Dave Mazur, Northrop Grumman’s B-2 vice president.

The Pentagon has not described the precise nature of the upgrades.

But program officials previously said reliability for the fuze has been troubling. Officials have also been working to develop a way for the weapon to lock onto a GPS signal sooner in flight.

Mazur says today’s weapon has a “very, very small miss distance [that] can literally be measured in feet.”

Ground testing of the upgraded MOP began this week, he says. Flight testing is soon to follow. He declined to say when the improved MOP will be fully integrated and delivered on the B-2 to the Air Force.

Also in the works for the B-2 is an upgrade for improved employment of the B61, the 700-lb. tactical nuclear weapon employed by the bomber. Today’s B-2 relies on an analog system for handling the weapon; that is slated to be switched to a more flexible and less obsolescent digital backbone, Mazur says.

Finally, early planning work has begun for what Mazur calls the “flexible strike” upgrade. Today, the B-2 is limited either to using a payload exclusive to the smart bomb rack or the rotary launcher; a mixed payload is not possible on the aircraft. Mazur says that the company is looking at how to implement such a mix to allow for more diverse payloads. Because work has only just begun, the project is at least a year away from officially beginning development.