U.S. President Donald Trump pinned the blame for the row between the U.S. and Turkey over the S-400 deal and F-35 jets on former president Barack Obama, saying it was not Erdoğan's fault, and it was Obama's administration who did not allow Ankara to buy Patriot missiles.

In his meeting with Recep Tayyip Erdoğan on Saturday on the sidelines of G20 summit in Japan, Trump slammed the Obama administration's reluctance ro sell Patriots to Turkey in 2013, saying Turkey was not treated fairly as a NATO member.

When asked about CAATSA or other sanctions against Turkey, Trump first severely criticized the unfair treatment of Turkey by the administration of Obama and said "we are looking at it, but it's [sanctions] a two-way street".

"They [Obama administration] wouldn't sell him [Erdoğan], they wouldn't let him buy the missile he wanted to buy which is the Patriot. And after he buys something else, they say now we will sell you the Patriot," Trump said.

"So I have to tell you, he [Erdoğan] is a NATO member and he is somebody I have become friendly with. And you have to treat fairly. You understand that? You have to treat fairly. I don't think he was treated fairly. I don't think he was treated fairly," Trump added, giving a clear sign that his administration will not seek the path of sanctions and avoid an unfair treatment of Turkey in the ongoing S-400 and F-35 tension. He said his administration would be looking at different solutions regarding the issue.

Trump said the two countries are "discussing" the S-400 issue, something he called a "complicated situation".

"The president [Erdoğan] was not allowed to buy the Patriot missiles, he wanted to do this, but he wasn't allowed by the Obama administration to buy them until after he made a deal to buy the other missiles. So he buys the other missile and then all of a sudden, they say you can buy our missile. You can't do business that way, it is not good. It is not good," said Trump.

"But he was prohibited from buying until he bought something else [S400]. And as soon as he buys something else, everybody says, okay you can buy it [Patriots]. You can't do business that way. Turkey has been a friend of ours," he added.

"We are doing great things together. We are big trading partners. We are going to be much bigger. I think $75 billion dollars [trade volume between nations] is small. I think it is going to be well over a $100 billion dollars. You can't treat people that way, like the way Obama administration did," he said, expressing his disappointment once again.

He called Erdoğan "a tough guy" but said he got along with him.

Trump also said he will visit Turkey soon. Asked if it will be in July, he said the date is not set yet.

The U.S. president dodged a question about the extrajudicial killing of journalist Jamal Khashoggi at the Istanbul consulate of the Saudi Kingdom, on alleged orders of Saudi Crown Prince Muhammad bin Salman.

Instead, he said the meetings with the Chinese president were much better than expected.