MIM-104 Patriot is not considered to be the best air-defense system available in the world. Recently, this system failed to prevent the Houthi rebels from targeting various oil refineries and storage facilities in Saudi Arabia using crude rockets. One of the staunches allies of the US, Turkey chose to purchase the S-400 system over the Patriot. The Russo-Ukrainian war has given an avenue for the Americans to get rid of these useless systems, in the name of defense aid to Ukraine. From what I have heard, these systems have proved quite inefficient against the Russian cruise and ballistic missiles.