President Donald Trump wrote a letter to Turkish President Recep Tayyip Erdogan saying that he can “destroy” the Turkish economy if Erdogan does not “work out a deal,” presumably over the country’s continued attacks on the Kurds in northern Syria.

In the letter, dated Oct. 9 and shared Oct. 16 by FOX Business on Twitter, Trump urges Erdogan to “work out a good deal,” saying “you don’t want to be responsible for slaughtering thousands of people.” The White House confirmed the authenticity of the letter to the PBS NewsHour.

READ THE FULL LETTER HERE:

The White House on Oct. 6 said that it was moving U.S. forces from northeast Syria following a call between Trump and Erdogan. For months earlier, Erdogan had been threatening to launch a military offensive into northern Syria, where Kurdish forces have been fighting alongside U.S. troops against ISIS. The withdrawal has essentially left the Kurdish fighters to both fight off ISIS and defend themselves from Turkish incursions, and has drawn bipartisan criticism on Capitol Hill and from other world leaders.

The White House defended the withdrawal by claiming that ISIS has been defeated. Intelligence experts say that’s not the case. Over the weekend, Trump’s former Defense Secretary Jim Mattis said ISIS was not defeated and will resurge without pressure from the U.S.-Kurdish partnership. The White House has also said that because the conflict is not on the U.S. border, U.S. troops “shouldn’t be losing lives over it.”

READ MORE: Trump wants out of ‘endless war,’ but pulling troops from northeast Syria could bring bloodshed