Trump on Tuesday told reporters before a White House cabinet meeting that Erdogan wanted to buy the US Patriot missile system, but the Obama administration would not sell it to him, and thus Ankara turned to Russia to supply the S-400 anti-aircraft missile system, Efe news reported.
"It's a mess. It's a mess, and honestly, it's not really Erdogan's fault," Trump had said at the G-20 summit in Japan. "I think he was unfairly treated."
"We are now telling Turkey that 'because you have really been forced to buy another missile system, we are not going to sell you the F-35 fighter jets,'" Trump said before the cabinet meeting.
Trump did not clarify what he meant by claiming that Ankara was "forced" to buy the Russian system.
The Pentagon announced in June that the sale of the F-35s to Ankara had been "postponed," and suggested that the US might exclude Turkey from the production chain of the aircraft, although that country manufactures hundreds of parts for the jet.
A few hours before Trump made his remarks on Tuesday, his nominee for US Defense Secretary, Mark Esper, called the agreement between Ankara and Moscow "disappointing" and said that Turkey could have either the Russian or US missile system, but it "cannot have both."
The focus of the controversy is on Russia's sale to Ankara of the $2.5 billion S-400 missile system, one of the showpieces of the Russian weapons industry. The ground-to-air missiles have a lethal range of 250 kilometers (155 miles).
Both the Pentagon and NATO, of which Turkey is a member state, have criticized the transaction since - quite apart from the thorny issue of buying weapons from NATO's biggest adversary - Russian weapons systems are not compatible with those of the Atlantic Alliance.
Nevertheless, Trump on Tuesday said that the situation was not "fair" to Turkey and expressed optimism about the possibility of finding an acceptable way out of the dilemma.
"I've had a good relationship with President Erdogan," Trump told reporters.
"It is a very tough situation that they are in, and it's a tough situation that we have been placed in, the United States ... With all of that being said, we're working through it - we'll see what happens," the US President added.
( With inputs from IANS )