Saudi Arabia is interested in buying 20 heavy cargo aircraft and five refueling planes from the US in a deal worth $6.7bn.
The deal, still to be approved by Congress, has been announced in a statement issued by the US Defence Security Cooperation Agency.
The multibillion-dollar deal also includes the cost of training, logistical support, parts and associated equipment for the aircraft, said the statement.
It said the deal would "help to improve the security of a friendly country that has been, and continues to be, an important force for political stability and economic progress in the Middle East".
It added: "Saudi Arabia needs these aircraft to sustain its aging fleet, which faces increasing obsolescence. The proposed sale of C-130J and KC-130J aircraft will provide a modern configuration, improve reliability and enhance the Royal Saudi Air Force’s ability to effectively field, support, and employ these aircraft."
Congress has 30 days to raise objections, otherwise the deal will be concluded.
Gulf countries are spending billions of dollars on defence procurement amid increasing tensions with Iran over its nuclear programme.
Foreign weapon sales by the United States tripled last year to $66.3bn as Gulf states sought to build up military supplies amid growing tensions with the Islamic Republic, according to a study by the US Congressional Research Service.
Earlier this month, Qatar requested to buy $9.9bn worth of missiles and defence equipment from the US just days after it placed an order for $6.5bn worth of missile-defence systems.
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