Donald Trump has announced fresh sanctions on Turkey and suspended negotiations on a $100bn (£79bn) trade deal, amid a mounting outcry over its assault upon Kurdish fighters as it invaded northern Syria.
The president signed executive orders to sanction the nation and will also boost tariffs on Turkish steel to 50 per cent.
In a statement Mr Trump vowed to "swiftly destroy" the Turkish economy if it continued down “this dangerous and destructive path”. He added that US troops coming out of Syria will redeploy and remain in the region to monitor the situation.
"The United States will aggressively use economic sanctions to target those who enable, facilitate, and finance these heinous acts in Syria," he added.
The US Treasury later said in a statement that action had been taken "against two [Turkish] ministries and three senior Turkish government officials in response to Turkey's military operations in Syria".
It added: "The Turkish government's actions are endangering innocent civilians, and destabilizing the region, including undermining the campaign to defeat Isis."
The White House also announced the president was sending Vice President Mike Pence to the Middle East, as tensions rose.
Mr Pence said Mr Trump spoke directly to Turkish leader Recep Tayyip Erdogan.
Mr Trump "communicated to him very clearly that the United States of American wants Turkey to stop the invasion, implement an immediate ceasefire and to begin to negotiate with Kurdish forces in Syria to bring an end to the violence,” Mr Pence said.
The US president appeared to backtrack on the green light he gave Ankara to launch its long-planned military operation into northeast Syria last week, after he pulled out a small number of US special forces who had been working with the Kurds, who soldiers had spearheaded the operation to destroy Isis.
Turkey began its offensive after the US pulled its military presence from northeast Syria, giving it the ability to attack the Kurdish fighters who had been a strong ally to American interests there.
Mr Trump has faced howls of opposition, notably from senior Republicans like Lindsey Graham, over his decision to withdraw from positions in northeast Syria.
Kurdish fighters who helped push back Isis as part of the Syrian Democratic Forces (SDF) have looked for new allies to push back against aggression from Turkey.
"You have given up on us. You are leaving us to be slaughtered," SDF general Mazloum Kobani Abdi told William Roebuck, the deputy special envoy to the global coalition to defeat Isis, during a meeting on Thursday. That conversation was detailed in an internal US government readout obtained by CNN.
"You are not willing to protect the people, but you do not want another force to come and protect us. You have sold us. This is immoral," he said.
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