Qatar's Ministry of Defence said that the deal would create 60,000 jobs in 42 USA states while reducing the burden on American forces.
The Pentagon did not provide additional details on the sale but Bloomberg reported it could include as many as 36 warplanes.
Despite the diplomatic crisis going on between Qatar and a number of its Gulf neighbors, the United States has agreed to sell $12 billion worth of American F-15 fighters to the country.
The biggest USA airbase in the Middle East is situated in Qatar and the country often helps USA troops in fights against Isis in Iraq and Syria.
The United States continues to send mixed messages as the row between two of its biggest allies in the Middle East, Qatar and Saudi Arabia, continues to get worse. Kuwait has led efforts to mediate the dispute which had affected food imports and raised questions over the Gulf Arab state's plans to host the 2022 World Cup.
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"ICAO is presently reviewing requests from the government of Qatar to assess the flight restrictions imposed upon it by neighbouring states", according to an ICAO statement.
Mattis formerly oversaw US Central Command whose forward operating base is the vast al-Udeid Air Base in Qatar - a hub for the global campaign against the so-called "Islamic State" (IS) in Syria and Iraq.
The US position was further muddied last Friday, when Tillerson called on Saudi Arabia to ease the blockade, only to have Trump, at a White House news conference hours later, say the blockade had been the right move. Qatar's ties with Iran, with whom it shares a major offshore natural gas field, is another criticism of the Arab countries.
"Just like other countries, like Saudi Arabia, the United Arab Emirates, Egypt.it is natural for Qatar to buy airplanes or parts necessary for its own defence", Cavusoglu said in Kuwait following talks with his Kuwaiti counterpart, according to Turkey's state-run Anadolu news agency.
Typically, Qatar Airways flights to the West flew over Saudi Arabia. Bahrain and the UAE have also made illegal expressions of sympathy for Qatar.
"We are working bring these states together towards a solution which satisfies both their current regional concerns and the global needs and expectations of passengers and shippers", ICAO said.
"We are friends, we've been friends now for a long time, haven't we?"