The U.S. State Department has approved a $1.75 billion sale to Saudi Arabia to upgrade its Patriot air defense system with PAC-3 missiles, a deal that would benefit Lockheed Martin Corp (LMT.N) and Raytheon Co (RTN.N), the Pentagon said Wednesday.

The Defense Security Cooperation Agency, which implements foreign arms sales, notified Congress on Wednesday about the potential arms sale, which must still be finalized. Lawmakers have 30 days to block the deal, although such action is rare.

DSCA said the deal would help Saudi Arabia replenish its current Patriot missiles, which are becoming obsolete and difficult to sustain due to age and lack of spare parts.

Lockheed, maker of the PAC-3 missiles, welcomed the congressional notification and said it was working with both governments as they discussed the potential sale.

If the deal is finalized, Saudi Arabia would become the eighth country to order PAC-3 missiles, joining the United States, the Netherlands, Germany, Japan, the United Arab Emirates, Taiwan and Kuwait.