Washington (CNN) The US Air Force has awarded a $2.38 billion contract to Boeing for new helicopters as part of an effort to replace the Vietnam-era "Hueys" that have been helping to secure America's nuclear missile sites.

The contract means the Air Force will purchase 84 MH-139 helicopters to replace the legacy UH-1Ns "Huey" helicopters currently performing the mission.

"The new helicopter will be an important tool for Airmen charged with securing and defending the nation's intercontinental ballistic missiles," the Air Force said in a statement Monday announcing the awarding of the first portion of the contract.

The MH-139 is a military version of the Leonardo AW139 helicopter and will be the product of a joint effort between Boeing and Leonardo and the MH-139s will be manufactured in Philadelphia, Pennsylvania.

"We're grateful for the Air Force's confidence in our MH-139 team," David Koopersmith, the vice president and general manager for Boeing Vertical Lift said in a statement.

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