The United States on Monday approved the sale of 25 F-16 fighter aircraft to Morocco for $3.8 billion, the State Department announced.

Besides the new Block 70/72 F-16s, equipped with state of the art electronic systems and weaponry, Washington also approved the modernization of 23 F-16s already in the Moroccan air force fleet, for $983 million.

The State Department said the sale would not affect the balance of forces in the region.

It can still be blocked by the U.S. Congress, which has 30 days to raise any objections.

More than 4,500 of the Lockheed Martin-built F-16s have been delivered since 1978.

It is gradually being replaced by the stealth F-35 fighters but more than 3,000 of F-16s are still in use in 25 countries, thanks to constant upgrades.

The Moroccan military ordered 24 F-16s in 2008. It lost one aircraft in action in 2015 during Saudi-led air operations in Yemen.