The Pentagon has announced that Boeing Co has been awarded a $2.1billion US defense contract.

The contract will be for an order of 15 KC-46 aerial refueling aircraft, which will go to the United States Air Force.

It is the third low-rate initial production lot for the new tankers, and includes spare engines and wing air refueling pod kits in addition to the 15 aircraft.

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The contract will be for an order of 15 KC-46 aerial refueling aircraft (pictured), which will go to the United States Air Force

The aircraft is based off the Boeing 767 air-frame, according to the Wichita Eagle.

Boeing expects to manufacture 179 jets for the Air Force to replace KC-135 fleet, which is over 50 years old.

Deliveries will begin later this year.

In addition to aircraft fuel, the tankers can carry passengers, cargo, and patients, Boeing said.

'This award is great news for the joint Boeing-Air Force team and reinforces the need for this highly efficient and capable tanker aircraft,' said Boeing Vice President and program manager Mike Gibbons in a statement.

'Our Boeing industry team is hard at work building and testing KC-46 aircraft, and we look forward to first delivery.'

'Placing an order for another 15 aircraft is another important milestone for the KC-46 program,' Air Force program manager Colonel John Newberry said in a statement.

'I know the warfighter is excited about bringing this next generation capability into the inventory.'

The Pentagon has announced this order and the $2.1billion contract, which will supply new jets to the Untied States Air Force

Chief Executive of Boeing, Dennis Muilenburg, has previously welcomed Trump's social media presence and habit of engaging with US companies on Twitter.

He has praised the new President for targeting companies like his, saying that he is 'directly engaging' with corporate America, reported the Financial Times.

Muilenburg praised his social media strategy and economic plans including tax reform, saying that he was giving business a 'voice at the table'.

He said to the Financial Times: 'I give him a lot of credit for reaching out and directly engaging'.

These comments came after Boeing was one of several US companies directly mentioned in one of the President's twitter rampages. He complained that the cost of Boeing's Air Force One replacement was too high.