The US Air Force has increased the cost ceiling on Northrop Grumman’s contract for B-2 bomber modernisation and sustainment work from $6.1bn to $9.54bn.

The contract for the air force’s long-range bomber is a purchase agreement known as an indefinite delivery, indefinite quantity contract, which will cover all Northrop Grumman’s activities on the B-2 programme.

The cost ceiling of an ID/IQ contract denotes the maximum possible value of products and services that can be acquired under that contract.

Northrop Grumman’s vice-president and B-2 programme manager Dave Mazur said that the move was pro-active.

“This will allow the B-2 industry team to continue critical modernisation and sustainment of one of the most powerful, most survivable assets in the nation’s defensive arsenal,” said Mazur.

The fleet of 20 B-2s, the only US aircraft that merge stealth, large payload, long range and precision weapons in one platform, is run by the 509th Bomb Wing in Missouri.