"The letter was written on 9 October. Erdogan rejected the offer of mediation and it was thrown into the trash. The clearest answer to this letter was the reply given at 4pm on 9 October. This is was the start of Operation Peace Spring," the official told local newspaper Yeni Safak.

But it apparently angered no one more than the recipient himself, according to the official, who recounted the incident to a Turkish newspaper on Thursday.

Images of the letter from Trump attempting to pressure Erdogan not to attack U.S.-allied Kurds in Syria became public on Wednesday and drew ridicule from critics in Washington.

A head-turning letter President Donald Trump wrote to his Turkish counterpart Recep Tayyip Erdogan apparently ended up in the trash, according to a senior Turkish official.

A letter from President Donald Trump to Turkey's President Tayyip Erdogan warning Erdogan about Turkish military policy and the Kurdish people in Syria is seen after being released by the White House. October 17, 2019

Trump, in the letter, threatened Erdogan with economic destruction if Turkey went forward with "slaughtering thousands of people," telling him, "Don't be a tough guy. Don't be a fool!"

He also wrote: "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," before concluding the letter with "I will call you later."

Several Democratic lawmakers and former government officials took to Twitter to call the letter "an embarrassment."

The Turkish foreign ministry did not respond to a request for comment when contacted by CNBC.

Turkey is now nine days into a military offensive that's so far produced harrowing reports of civilian casualties, ISIS jailbreaks and human rights atrocities, according to activists and aid groups. The U.N. says more than 130,000 people have already been displaced.

The Turkish official's story comes with U.S. officials in Ankara trying to reach a cease-fire, doing what's been described as damage control after Trump's Oct. 6 announcement to withdraw U.S. troops from northern Syria and allow Turkey to carry out its own operations in the territory.

Trump's decision was widely criticized as abandoning America's Kurdish allies in northern Syria and allowing for the resurgence of ISIS. The Kurdish militia groups proved vital in driving ISIS out of the country alongside U.S. troops, but are viewed by Ankara as terrorists.

Critics accuse Trump of greenlighting the offensive by Turkey, something the president has denied while defending his decision as a means of bringing U.S. troops back home and letting other countries deal with ISIS.

A House resolution condemning Trump's decision to remove U.S. forces from the area was overwhelmingly approved on Wednesday in a bipartisan vote of 354-60.