(Adds Lockheed statement)

WASHINGTON, July 29 (Reuters) - The U.S. State Department has approved the possible sale to Saudi Arabia of $5.4 billion in additional PAC-3 missiles built by Lockheed Martin Corp , the Pentagon said on Wednesday.

The Defense Security Cooperation Agency said the sale would benefit a key U.S. partner in the Middle East. Notification to Congress was sent on Tuesday and follows a major nuclear deal with Iran. The missile sale approval could help reassure Saudi Arabia about the U.S. commitment to its security.

"Lockheed Martin is supporting the U.S. government and the kingdom of Saudi Arabia as they discuss the potential sale of additional PAC-3 Missiles as part of the upgrade of the Royal Saudi Air Defense Force," Lockheed said in a statement.

The company said the PAC-3 missile defends against incoming aircraft and missiles, and it is currently used by the United States, the Netherlands, Germany, Japan, Taiwan and the United Arab Emirates.

(Reporting by Andrea Shalal; Editing by Bill Trott and Emily Stephenson) ((andrea.shalal@thomsonreuters.com))

Keywords: USA SAUDI/MISSILES