After announcing his decision to pull US troops from northeastern Syria, Donald Trump issued a warning to Turkish President Recep Tayyip Erdogan: "Don't be a tough guy."

According to a letter obtained by Fox Business' Trish Regan, Trump urged Erdogan to excercise military restraint and reach a peaceful resolution with Kurdish General Mazloum Kobani. The letter was dated Oct. 9, the same day Turkish forces launched their offensive against the Kurds. 

"Let’s work out a good deal!" the letter states. "You don’t want to be responsible for slaughtering thousands of people, and I don’t want to be responsible for destroying the Turkish economy — and I will. I've already given you a little sample with respect to Pastor Brunson."

Andrew Brunson is an evangelical pastor who was imprisoned in Turkey back in 2016 for allegedly aiding a failed coup attempt against Erdogan. He was eventually released in October 2018, after Trump imposed sanctions on Turkey.

"I have worked hard to solve some of your problems. Don’t let the world down," the letter continued. "You can make a great deal. General Mazloum is willing to negotiate with you, and he is willing to make concessions that they would never have made in the past. I am confidentially enclosing a copy of his letter to me, just received.

"History will look upon you favorably if you get this done the right and humane way. It will look upon you forever as the devil if good things don't happen. Don't be a tough guy! Don't be a fool!"

The White House has confirmed the letter's authenticity to the New York Times, after many questioned whether Trump would send such a bizarrely worded warning. 

Trump alluded to the letter during Wednesday's press conference with Italian President Sergio Mattarella. The president was asked about the backlash he received for withdrawing from northern Syria, as many considered the move a betrayal to Kurdish allies who have helped in the fight against ISIS. Critics say the decision was essentially a green light for the Turkish military to attack the Syrian Democratic Forces, as they are significantly more vulnerable without U.S. assistance.

"I didn't give them a green light, and if anybody saw the letter, which can be released very easily, if you would like, I can certainly release it," Trump told reporters Wednesday. "But I wrote a letter right after that conversation, a very powerful letter. There was never given a green light. They’ve been wanting to do that for years, and frankly, they've been fighting for many, many years."