U.S. President Donald Trump wrote a candid, rather aggressive letter to Turkish President Recep Erdogan last month in which he threatened to crash Turkey’s economy and warned him to not be a “fool” and become “the devil” over military action in Syria.

The letter, sent in October, urged Erdogan to strike a deal with Kurdish forces in northern Syria rather than invade. During a visit to the White House yesterday, Erdogan was asked why he ignored Trump’s letter, which he said he returned to sender yesterday.

“This letter was re-presented to the president this afternoon,” Erdogan told reporters, reviving a diplomatic fight. The letter was shocking to many with its language, which included a specific threat from Trump to sink Turkey’s economy if the Turkish president didn’t back down in Syria.

“Let’s work out a good deal! 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,” Trump wrote. “I’ve already given you a little sample with respect to Pastor Brunson.

“I have worked hard to solve some of your problems. Don’t let the world down. 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 confidently 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!”

Turkish sources reportedly told media outlets at the time that the letter had been thrown away.

Erdogan told reporters during Wednesday’s press conference that Turkish military intervention in Syria was part of the fight against terrorism, as Ankara regards the Kurdish fighters as terrorists that work with separatist groups within Turkey.

The United Nations estimates that nearly 200,000 people have been displaced because of Turkey’s military action in the region after the U.S. suddenly decided to pull troops last month at Trump’s order.