The US Air Force has awarded an $11.9bn contract to Boeing for the modernisation of the B-52 Stratofortress weapon system.

Under the eight-year contract, Boeing will carry out engineering, sustainment activities, studies and production in support of the B-52 bomber.

The first US long-range heavy bomber, the B-52 was developed to carry nuclear weapons and has been used in missions in the Vietnam War, the 1991 Gulf War and Afghanistan.

The current B-52 Stratofortress versions can be used for long-range missions and transport, and can also be armed with ballistic missiles that can be launched hundreds of miles from their targets.

Boeing has been providing maintenance, engineering services and upgrades to communication technology of the aircraft for 55 years.