The contract, believed to be the largest U.S. arms sale this year, was signed in Washington Monday by U.S. Defense Secretary Chuck Hagel and his Qatari counterpart, Hamad bin Ali al-Attiyah.
"Today's signing ceremony underscores the strong partnership between the United States and Qatar in the area of security and defense and will help improve our bilateral cooperation across a range of military operations," said Pentagon spokesman Rear Adm. John Kirby in a statement.
The two countries signed a 10-year defense cooperation agreement in December, and Washington regards the improvement of its Gulf allies' air defenses a priority.
Qatar was instrumental in the release in May of Sgt. Bowe Bergdahl, held for five years by the Taliban, in exchange for five Taliban leaders held by the United States at Guantanamo Bay, Cuba.