While 2015 isn’t even over yet Saudi Arabia has already ordered over $6 billion worth of ammunition. A small portion of this was smart bombs and missiles for Saudi Operations (mainly in the air) against ISIL in Iraq and Syria and Shia rebels in Yemen. Most (90 percent) of that money went to buy 600 more American PAC-3 anti-missile missiles. These are mainly to defend the Saudis from Iranian ballistic missiles, but also the similar North Korean ballistic missiles in Yemen that have been captured by the Shia rebels and used, in at least two cases, against Saudi targets.
In late 2014 Saudi Arabia spent $1.75 billion on 202 PAC 3 anti-missile missiles for its Patriot missile batteries. This included support and training equipment as well as modifications to existing Saudi Patriot equipment so they can handle the PAC 3 missile.
Since the 1990s Saudi Arabia has invested billions of dollars on air defense systems, mainly the American Patriot system. The Saudis have bought four battalions (24 batteries) of Patriots. Each Patriot battery is manned by about a hundred troops, and contains a radar, plus four launchers. A battery can fire two types of Patriot missile. The more expensive PAC 3 missile is smaller than the anti-aircraft version (PAC 2), thus a Patriot launcher can hold sixteen PAC 3 missiles, versus four PAC 2s. A PAC 2 missile weighs about a ton, a PAC 3 weighs about a third of that. The PAC 3 has a shorter range (about 20 kilometers (although the latest version can do 35 kilometers) versus 160 kilometers for the latest anti-aircraft version.
Patriot entered service in 1981 and since then over 1,200 launchers and more than 10,000 missiles have been produced. About ten percent of the Patriot systems were exported. These days some of the best customers are found in the Middle East.