Secretary of State Mike Pompeo is defending President Trump's decision to remove US troops from Syria.
Col. Ryan acknowledged the US withdrawal in Syria had commenced Friday, but withheld details of specific military plans on troop movements. "Will attack [ISIS] again from existing nearby base if it reforms".
Last week, Turkish President Recep Tayyip Erdoğan publicly lashed out at USA national security adviser John Bolton for saying the U.S. withdrawal was contingent upon Turkey's pledge not to attack US-backed Kurdish fighters in Syria once troops leave.
Once the troops are gone, the U.S. will have ended three years of organizing, arming, advising and providing air cover for Syrian, Kurdish and Arab fighters in an open-ended campaign devised by the Obama administration to deal the militants, also known as ISIS, a lasting defeat.
Turkish President Recep Tayyip Erdogan has threatened to "crush" Kurdish fighters in Syria.
Senior US officials were shocked too, among them Defense Secretary Jim Mattis, who quit in protest.
Speaking in Abu Dhabi later in the day, Pompeo said there were still many details to be worked out with Turkey but he was optimistic that a "good outcome" can be achieved that protects Turkey from legitimate terror threats, after speaking to the Turkish foreign minister.
Turkey on Saturday welcomed the latest statement made by Washington's top diplomat over Ankara's right to defend itself from "terrorists" after the USA withdraws from Syria.
He called the Syria pullout "long overdue" but said the USA would still hit "the little remaining Isis territorial caliphate hard, and from many directions".
But Mr Trump attempted to reassure both Syrian Kurds and observers anxious about a potential ISIS resurgence, saying U.S. troops would remain across the border in Iraq to enforce a 20 mile safe zone.
"We also know that those who aren't terrorists, those who were fighting alongside of us for all this time deserve to be protected as well", Pompeo said.
Ankara has repeatedly told Washington that the YPG is not different from the PKK as the groups were intertwined, and partnering with one terrorist group to fight another was not acceptable.
The Turkish government has said Kurdish fighters are linked to a group that has been mounting an insurgency against the Turkish state for decades. "The bulk of recent attacks show how we are more committed than ever to act against Iran in Syria, as we promised".
Sousan said intensified dialog was important when set against challenges, "especially the expansionist ambitions that lead the policies of the Turkish regime".