"It's not solely about Iran. It's about helping the Saudis with their legitimate security needs, and they have a number of legitimate security needs. They live in a dangerous neighborhood and we are helping them preserve and protect their security in a dangerous neighborhood against legitimate security threats," said Shapiro.

Assistant Secretary of Defense for International Security Affairs Alexander Vershbow said the buildup of Saudi capabilities could eventually reduce the need for U.S. military deployments in the Gulf region.

"When one looks at future challenges, having allies throughout the Gulf region who are inter-operable with U.S. forces, who are capable, who have trained together with our forces, it means we have partners and allies we can look to in future contingencies," said Vershbow. "So it means we may have to station fewer forces on a continuing basis in the region."

Vershbow said the United States has had high-level consultations with Israeli officials on the pending sale, and that Israel does not object to it.

Israel has long had U.S. F-15 fighters in its arsenal and recently has committed to purchase new F-35 strike fighter jets, which U.S. officials say will preserve Israel's qualitative military advantage in the Middle East.

The U.S. Congress could block the Saudi arms deal. Assistant Secretary Shapiro said, however, that contacts with key House and Senate leaders make administration officials confident that Congress will not be a barrier to the completion of the sale.