Trump said earlier this week the United States would step aside for an expected Turkish attack on Syrian Kurdish fighters, who have fought alongside Americans for years, but he then threatened to destroy the Turks' economy if they went too far.
The U.S. president later cast his decision to abandon the Kurdish fighters in Syria as fulfilling a campaign promise to withdraw from "endless war" in the Middle East, even as Republican critics and others said he was sacrificing a U.S. ally and undermining American credibility.
Trump's statements have reverberated on all sides of the divide in Syria and the Mideast.
In Ankara, Turkish Vice President Fuat Oktay said Turkey was intent on combatting Syrian Kurdish fighters across its border in Syria and on creating a zone that would allow Turkey to resettle Syrian refugees there.
"Where Turkey's security is concerned, we determine our own path but we set our own limits," Oktay said.
Meanwhile, in the Syrian capital of Damascus, Deputy Foreign Minister Faisal Mekdad called on the country's Kurds to rejoin the government side after apparently being abandoned by their U.S. allies.
Mekdad's comments were the first Syrian reaction since Trump's announcement on Sunday and as northeastern Syria braces for an imminent Turkish attack on Syrian Kurdish militias. Trump's statement has infuriated the Kurds, who stand to lose the autonomy they gained from Damascus during Syria's civil war, now in its ninth year.
"The homeland welcomes all its sons and Damascus will solve all Syrian problems in a positive way, away from violence," Mekdad said in an interview with the pro-government daily Al-Watan.
As for the expected Turkish incursion, he added that the Syrian government "will defend all Syrian territory and will not accept any occupation of any land or iota of the Syrian soil."
The Syrian Kurdish force has pledged to fight back, raising the potential for an eruption of new warfare in Syria.
"We will not hesitate for a moment in defending our people" against Turkish troops, the Kurdish-led Syrian Democratic Forces said in a statement, adding that it has lost 11,000 fighters in the war against the Islamic State group in Syria.
Turkey, which considers Kurdish fighters in Syria terrorists and links them to a decades-old insurgency in Turkey, has already launched two major incursions into northern Syria over the past years. The first was in 2016, when Turkey and Syrian opposition fighters it backs attacked areas held by the Islamic State group west of the Euphrates River. Last year Turkey launched an attack on the Syrian Kurdish enclave of Afrin, leading to the displacement of some 300,000 people.
"We tell them that they have lost everything and must not lose themselves," Mekdad added.
Also Tuesday, Iran urged Turkey not to go ahead with its planned an attack on Syrian Kurds, the Iranian state TV reported. Foreign Minister Mohammad Javad Zarif called his Turkish counterpart, Mevlut Cavusoglu, to express Tehran's opposition to the anticipated Turkish operation.
Zarif urged Turkey to respect Syria's integrity and sovereignty, the report said.
Iran, Turkey and Russia have been working together as part of the so-called Astana group on the Syrian civil war, talks that have run parallel to U.N. efforts to find a solution to the conflict.
Trump's announcement threw the military situation in Syria into fresh chaos and injected deeper uncertainty into the region.
U.S. involvement in Syria has been fraught with peril since it started in 2014 with the insertion of small numbers of special operations forces to recruit, train, arm and advise local fighters to combat the Islamic State. Trump entered the White House in 2017 intent on getting out of Syria, and even before the counter-IS military campaign reclaimed the last militant strongholds early this year, he declared victory and said troops would leave.
In recent weeks, the U.S. and Turkey had reached an apparent accommodation of Turkish concerns about the presence of Kurdish fighters, seen in Turkey as a threat. American and Turkish soldiers had been conducting joint patrols in a zone along the border. As part of that work, barriers designed to protect the Syrian Kurds were dismantled amid assurances that Turkey would not invade.