Russia's S-400 Air Defense System

One use of the S-400 long-range missile is against stand-off systems including flying command posts and aircraft such as the E-3 Sentry AWACS. These aircraft, which are used by the US and its NATO allies with a squadron stationed in Japan at Kadena AFB and in the UAE at al-Dhafra, are vulnerable to S-400 interceptors and lose their stand-off range protection. We may be reaching the end of the AWACS capability, which were originally designed in the 1960s. The S-400 also has capability against ballistic missiles, a feature that surely attracted Saudi Arabia’s interest. How good is it against ballistic missiles? No one knows for sure.The Saudi decision to buy the S-400 is probably linked to Egypt’s earlier purchase of the S-300VM and desire to get the S-400. Saudi Arabia and other Gulf states probably paid for Egypt’s weapons.