Saudi Arabia is paying $15 billion for this advanced anti-missile system

The Pentagon says the US State Department has approved the possible sale of the advanced THAAD missile-defense system to Saudi Arabia for $15 billion, citing Iran among threats in the Middle East.

The Pentagon's Defense Security Cooperation Agency said in an Oct. 6 statement that it had notified the US Congress about the possible sale, saying the deal would "support the foreign policy and national security objectives of the United States."

"This sale furthers US national security and foreign policy interests, and supports the long-term security of Saudi Arabia and the Gulf region in the face of Iranian and other regional threats," the statement said.

Washington deployed THAAD, which is used to guard against ballistic-missile attacks, to South Korea this year for defense against North Korea.

Iran maintains one of the largest ballistic-missile programs in the Middle East, seeing it as a key element of defense against the United States and other opponents, including Israel and Gulf Arab states.

Both Washington and Saudi Arabia accuse Tehran of aggressive and disruptive behavior in the region.