“We’re going to see more of this,” Karako said. “So long as the Iranian missile threat exists, GCC and other countries in the region are going to have to invest in counters offensive and defensive.”

Iran has the largest and most diverse missile program in the Middle East, made up of short-range, long-range, anti-ship and cruise missiles, experts say. Middle Eastern nations have as little as four minutes to act if Iran fires one of these missiles their way.

Middle Eastern nations are also likely to boost buys of Terminal High Altitude Area Defense, or THAAD, interceptors, which can reach farther than Patriot to shoot down missiles.

UAE has already purchased THAAD and Saudi and Qatar are interested in the system. Also likely to pick up steam is the sale of a massive missile-tracking radar to Qatar.

The U.S. has been urging the GCC members to network their missile defense equipment together to better detect launches and so multiple countries don’t fire interceptors at the same missile.

The Saudi deal announced Wednesday is for the newest version of Patriot, called PAC-3. “The proposed sale will modernize and replenish Saudi Arabia’s current Patriot missile stockpile, which is becoming obsolete and difficult to sustain due to age and limited availability of repair parts,” the Pentagon wrote in its required notification to Congress of the deal. “The purchase of the PAC-3 missiles will support current and future defense missions and promote stability within the region.”

In June, Saudi Arabia used a Patriot to shoot down a Scud missile launched by Houthi rebels in Yemen.