The US is asking for 1.62 billion dollars to upgrade 85 F-16 fighter jets belonging to the Hellenic Air Force to F-16Vs or Block 70s, Kathimerini understands.
The price tag is significantly higher than the 1.1 billion dollars announced by the government and the prime minister in Parliament.
Sources close to the negotiations said the final price will probably be settled at 1.5 billion dollars (around 1.28 billion euros).
The letter of offer and acceptance sent by the US is valid until January 31, 2018.
Even though the deadline is not binding, both sides are eager to conclude the deal within this time frame.
According to reports, payments in 2018 will be covered by the air force budget, but there will be difficulties in 2019 when Greece will have to purchase the parts and equipment needed to complete the upgrade.