In looking to upgrade their air defense system, Turkey had a choice: buying the advanced Russian S-400 systems, or more expensive, US-made alternatives. Turkey chose to buy Russian, and NATO isn’t happy.

While NATO was initially just complaining the S-400 was incompatible with their own systems, top NATO General Petr Pavel told reporters this week that Turkey is likely to be punished by the alliance for not buying American.

“The principal of sovereignty obviously exists in acquisition of defense equipment, but the same way that nations are sovereign in making their decision, they are also sovereign in facing the consequences of that decision,” Pavel insisted.

Pavel dismissed reporter questions about the Turkish government’s recent anti-democracy moves, insisting nobody is perfect. Apparently the same leeway does not apply for the question of buying American weapons.

Russia’s S-400, and its predecessor the S-300, have been praised as advanced, cost-effective alternatives to American anti-aircraft systems. The US is used to having a virtual monopoly on this market, by ensuring that no one buys Russian without facing some very public criticism.