The Patriot system actually has seen substantial changes since the first Gulf War. The first Gulf War used what are called 'PAC-2' systems. They've since develo

The Patriot system actually has seen substantial changes since the first Gulf War. The first Gulf War used what are called 'PAC-2' systems. They've since developed and deployed PAC-3 systems. The list of changes is comprehensive. If nothing else, it uses a new missile that was designed from scratch to act in an anti-ballistic missile role (the PAC-2 used a missile designed for aircraft intercept - the two roles have really different end-game requirements). The radar, the intercept software on the missile itself, mission management software have all been modified. The PAC-2 missile relied on its ground based radar to guide it onto the target, and relied on an explosive warhead to damage the target. The PAC-3 has an integrated radar to guide itself onto target and is capable of hit to kill intercept. Now, those are all the claims anyways. We'll have to see how useful all these changes actually were.