"I've had a good relationship with President [Recep Tayyip] Erdogan," US President Donald Trump told reporters during a Cabinet meeting.
US President Donald Trump said on Tuesday the situation with Turkey is not fair because Turkey wanted to buy US Patriot missile systems and Washington wouldn’t sell to Ankara.
"It's a very tough situation that they're in. And it's a very tough situation that we've been placed in the United States," Trump told reporters during a Cabinet meeting at the White House.
"With all of that being said, we're working through it. We'll see what happens, but it's not really fair," he added.
Trump said it was "foolish" for the US to not sell Patriots to "NATO member" Turkey.
"They were not allowed to buy Patriots here foolishly, and Turkey is a NATO member," Trump said.
"I've had a good relationship with President [Recep Tayyip] Erdogan," Trump told journalists.
TRT World's Courtney Kealy has more from Washington.
Trump said Turkey was forced to buy the S-400 system by his predecessor Barack Obama, leading the Pentagon to halt plans to sell F-35 fighter jets to the country.
The US administration had threatened to expel Turkey from the F-35 fighter programme if it acquired the S-400 from Russia, warning the anti-air system could be used by Moscow to covertly attain secret information on the stealth fighter.
The delivery of S-400 components began last week and is ongoing. Turkey's Defense Ministry said a twelfth Russian plane with the anti-air parts landed at Murted airfield outside Ankara on Tuesday.
Following protracted efforts to purchase an air defence system from the US with no success, Ankara signed a contract in 2017 to purchase the S-400s from Russia.
The US halted in June training for Turkish pilots as a step in winding down Turkey's participation in the F-35 programme.
Washington has also threatened sanctions over Turkey's purchase, with Ankara responding that any sanctions would be met in kind.