Relations between the USA and Turkey have soured following the purchase by Turkey of a Russian missile defense system. Turkey received the first deliveries of the Russian-made S-400 missile defense system on Friday. The USA had warned Turkey not to buy defense equipment from Russia. The USA and Turkey are both allies in NATO - a defense organization created in 1949 to counter any possible military aggression by Russia. NATO consists of 29 North American and European nations. The USA has the biggest military among the member states. In recent years, Turkey has been establishing closer ties with Russia. This has caused security concerns for the USA and other NATO member countries.
The U.S. has warned Turkey it will face economic sanctions if it goes ahead and installs the S-400 defense system. It also said Turkey would not be allowed to play any part in a program to manufacture the USA's high-tech F-35 fighter jets. The U.S. wants Turkey to buy its Patriot missile defense system instead. U.S. officials argue the Russian system would be incompatible with NATO systems and would expose F-35 fighter jets to possible Russian subterfuge. Turkey said the S-400 would not be integrated into NATO systems and would not pose a threat to the NATO alliance. Turkey's president said the decision to purchase the S-400 system did not mean it is seeking "alternatives" in its relations with the West.