Giant US aerospace and defence group Boeing announced on Monday that it had been awarded a $1.6-billion sole-source service contract by the US Air Force (USAF). Under the contract, the corporation will service and maintain the guidance systems of the USAF’s land-based Minuteman III intercontinental ballistic missiles (ICBMs). The duration of the new contract is 18 years. Boeing has been maintaining the Minuteman III guidance systems, without a break, since 1996.