U.S. President Donald Trump tweeted late on Sunday that the US will “devastate Turkey economically if they hit Kurds."  “Will devastate Turkey economically if they hit Kurds,’ Trump said on Twitter, while also calling on Kurds not to provoke Ankara.  Turkey has responded furiously to a threat from Trump to devastate its economy if they attacked Kurdish partners in Syria.

“Starting the long overdue pullout from Syria while hitting the little remaining ISIS territorial caliphate hard, and from many directions. Will attack again from existing nearby base if it reforms,” Trump said.  “Will devastate Turkey economically if they hit Kurds.  Create 20 mile safe zone…Likewise, do not want the Kurds to provoke Turkey.”

Early Monday, President Recep Tayyip Erdogan’s spokesman said Turkey would continue to fight the U.S.-backed Syrian Kurdish militia, known as YPG, according to The Wall Street Journal (WSJ).

“[Mr. Trump], terrorists can’t be your partners & allies. Turkey expects the U.S. to honor our strategic partnership and doesn’t want it to be shadowed by terrorist propaganda,” spokesman Ibrahim Kalin said in a statement.  “There is no difference between DAESH, PKK, PYD and YPG. We will continue to fight against them all,” he said, using acronyms for Islamic State and Kurdish groups.

The Telegraph reports Turkish Foreign Minister Mevlut Cavusoglu sharply rebuked Mr. Trump, saying that strategic partners do not speak to each other through social media and stressing that Turkey is "not afraid of any threat. You cannot achieve anything with economic threats."

"We would do whatever is necessary to eliminate threat to our security," said Mr. Cavusoglu, adding that Ankara saw the Kurdish People’s Protection Units (YPG) as terrorists who needed to be defeated.

The Telegraph notes that asked to explain the tweet, Mike Pompeo, US Secretary of State, said he assumed Mr. Trump was referring to the imposition of sanctions should Ankara take military action against the YPG, its allies in the fight against Islamic State of Iraq and the Levant (ISIL).

Mr. Trump imposed sanctions and trade tariffs on Turkey in August to pressure them to release an American pastor who had been arrested on charges of supporting a failed 2016 coup against Mr. Erdogan.

Relations between Turkey and the US have soured in recent years over the issue of Washington’s support for the YPG, and has only been made worse by the US’s confused messaging on its withdrawal of troops from Syria.

According to WSJ, Mr. Trump’s national security adviser, John Bolton, said last week that the U.S. withdrawal from Syria is contingent on whether Turkey can guarantee the safety of the Kurdish forces across its border.  His statement reportedly enraged the government in Ankara just as he was set to arrive there, prompting Mr. Erdogan to refuse to meet with Mr. Bolton.  Later that day, Mr. Erdogan delivered a speech to parliament saying that Mr. Bolton had made a “serious mistake.”

Turkey has insisted for years that Syria’s Kurdish rebel groups are terrorists and pose an existential threat. Turkish officials had applauded the U.S. decision to leave Syria and end its partnership with the Kurdish YPG militia, but were quickly put off when the U.S. later called on Turkey not to take any action against the Kurds in northern Syria.

Kurdish fighters have long provided the U.S. with support in the campaign against Islamic State. But Turkey considers itself justified in targeting those fighters, and doesn’t draw distinctions between those groups and Islamic State and other militant groups.