The Turkish president said he returned the letter Trump sent him last month, advising Erdogan to "not be a fool".

"The letter was sent back to President Trump this afternoon," Tayyip Erdogan said at a White House press conference on November 13 during the official visit to the United States, when asked by reporters why he ignored his advice. President of the United States and opening a military campaign against the Kurds in Syria.

The letter the President of Turkey mentioned to Trump was sent to him on October 9, after Ankara announced plans to conduct a military campaign of Spring Peace in northern Syria. In the letter, the US President advised Erdogan to "put together a sound agreement" for the Syrian issue. "Don't be a stubborn person. Don't be a fool," the letter said.

"We returned the letter we received," Erdogan stressed on November 13, as a way of denying previous information that he had thrown Trump's letter into the trash.

Turkey launched a military campaign into northern Syria against Kurdish militias, which Ankara accuses of being "terrorists," after Trump agreed to withdraw all troops from the region.

After much criticism of the decision, Trump changed his mind and asked Vice President Mike Pence to launch a deal with Turkey to end the fighting in northern Syria.

Just before the Turkish president's US visit, a bipartisan congressional group sent a letter to Trump, urging him to cancel Erdgogan's invitation to visit the US, saying the timing was "particularly inappropriate". However, the President said that he and his Turkish counterpart had "been friends for a long time".