Turkish Defense Minister Hulusi Akar said it would be "very problematic" for Ankara to turn back on its purchase of Russian S-400 defense systems, but expressed hope that a dispute with the United States on the issue could be resolved through dialogue.

Akar also reiterated that Turkey was in talks with Russia on obtaining a second consignment of the S400 defense systems.

Washington slapped sanctions on NATO ally Turkey's Defense ­Industry Directorate (SSB), its chief Ismail Demir and three other employees in December following its acquisition of the S-400s.

"It is a very problematic situation to turn back from the point we have come to. We invite [the US] to distance themselves from threatening language such as sanctions," Akar told journalists in Ankara.

"We want the solution of problems through dialogue. If the US side wants a solution, a solution could be found with work on the technical level," he said.

The sanctions were imposed at a challenging time in the fraught relationship between Ankara and Washington. 

US President-elect Joe Biden is set to take office on January 20, replacing Donald Trump. 

Biden has been critical of Turkish President Tayyip Erdogan's policies in the past.

Turkey has defended its acquisition of the S-400s as a necessity because it was unable to procure air defense systems from any NATO ally on satisfactory terms.

Washington says the S-400s pose a threat to its F-35 fighter jets and to NATO's broader defense systems. 

Turkey rejects this and says S-400s will not be integrated into NATO.