The head of Turkey's Nationalist Movement Party (MHP) on Wednesday condemned the US move to impose sanctions on Turkey.
Devlet Bahçeli labelled the US sanctions as "scandalous, disrespectful and rude."
Turkey does not need any approval from the US to purchase weapons, Bahçeli said.
In April 2017, when its protracted efforts to buy an air defense system from the US proved fruitless, Turkey signed a contract with Russia to acquire the S-400 shield.
US officials have voiced opposition to their deployment, claiming they would be incompatible with NATO systems and would expose next-generation F-35 jets to possible Russian subterfuge.
Turkey, however, stressed that the S-400 would not be integrated into NATO systems, and posed no threat to the alliance or its armaments.
It has repeatedly urged a working group to clear up the technical compatibility issues.
The US on Monday imposed sanctions on Turkey over its purchase of the Russian S-400 missile defense system.
The sanctions, coming under the Countering America's Adversaries Through Sanctions Act (CAATSA), target the Defense Industries Presidency (SSB), including Head of SSB Ismail Demir and three other officials.
