Expectations of a Turkish invasion rose after President Donald Trump on Sunday abruptly announced that American troops would step aside ahead of the Turkish push - a shift in USA policy that essentially abandoned the Syrian Kurds, longtime US allies in the fight against the Islamic State group in Syria. It's considered a terrorist organization by the US and the European Union.
Given that those same Kurdish groups have fought alongside U.S. forces against the Islamic State movement in Syria, Trump's decision was seen by prominent figures of his own Republican party as a betrayal. But the Kurds' aspirations for regional autonomy have complicated the relations between the USA and its North Atlantic Treaty Organisation ally Turkey, which sees the Kurds' presence on its border as a threat and labels their fighters terrorists.
Votel and Dent said the move "could not come at a worse time" and was made "without consulting USA allies or senior US military leadership".
Russian Foreign Minister Sergei Lavrov on Wednesday warned of the risks of Washington sending mixed signals on an American withdrawal from northern Syria. Pentagon sources said about 100 USA personnel were relocated.
Iranian President Hassan Rouhani called on Turkey to show restraint and avoid military action in the region, adding that USA forces should leave the region.
Turkish commanders expect to be confronted by a sophisticated foe after the battle-hardened YPG were armed by the US and other Western militaries to help fight Islamic State, they said. "We are helping the Kurds financially/weapons!"
"This is a separatist terrorist organisation and wants to divide Syria, while we support Syria's territorial integrity".
But US President Donald Trump warned he would "obliterate" the North Atlantic Treaty Organisation ally's economy if it took action in Syria that he considered "off limits", following his decision on Sunday to pull at least 50 American special forces troops from the border region. "Abandon allies and embolden adversaries".
Trump's announcement has received broad criticism from both Republicans and Democrats in Congress.
And Sen. Lindsey Graham of SC, a close national security adviser of Mr. Trump's, blasted what he called "the impulsive decision by the president" as "shortsighted and irresponsible".
Since the 2016 campaign, Mr. Trump has been clear about his objective to get the USA out of what he calls "these ridiculous endless wars".
The Kurdish-led forces have said they may launch talks with Damascus or Moscow to fill a security vacuum in the event of a full USA withdrawal from the area.
But that precipitous decision led to the departure of then-Defense Secretary Jim Mattis.
There are also signs other players in the region are waiting to take advantage of any Turkish-Kurdish conflict.
The Kurdish-led Syrian Democratic Forces said they would defend their "own people", potentially relegating the battle against Islamic State. "As a result we have moved the U.S. forces in northern Syria out of the path of potential Turkish incursion to ensure their safety", U.S. Defense Department spokesman Jonathan Hoffman said in a statement. "We haven't done so in Jarablus when we fought against Daesh and eliminated 3,000 terrorists there...or when we entered Afrin, we have not occupied any part of Syria, we have returned those places to the local owners and residents, we have no intention of occupying any parts of Syria in the east of the Euphrates either, and also we have no interest in changing the demographics there".
But Sunday night the White House released a statement saying the president had spoken with Mr. Erdoğan, and that "Turkey will soon be moving forward with its long-planned operation into Northern Syria".
The U.S. withdrawal from the area will leave Kurdish-led forces long allied to Washington vulnerable to attack by the Turkish Armed Forces (TSK).
Kurdish-led forces have denounced the US policy shift as a "stab in the back".
Also on Wednesday, the PYD ruling parts of northeastern Syria called up civilians to head to the border with Turkey ahead of planned Turkish operation.