JERUSALEM - White House national security adviser John Bolton added a new condition on Sunday to the US withdrawal from Syria, saying Turkey must agree to protect the United States' Kurdish allies.

President Donald Trump's abrupt decision to announce a US pullout from Syria left many questions open, chiefly whether Kurdish fighters who had been operating in northern Syria alongside US forces would now be attacked by their long-time enemy, Turkey.

Bolton, on a trip to Israel and Turkey, said he would stress in talks with Turkish officials, including President Tayyip Erdogan, that Kurdish forces must be protected.

Ahead of talks with Israeli officials, he told reporters the pullout would be done in a way that guaranteed the Islamic State jihadist group "is defeated and is not able to revive itself and become a threat again."

And it would be carried out in such a way as to "make sure that the defense of Israel and our other friends in the region is absolutely assured, and to take care of those who have fought with us against ISIS and other terrorist groups."

Asked whether a US withdrawal would not take place in Syria until Turkey guaranteed the Kurdish fighters would be safe, Bolton said: "Basically, that's right."

The Syrian YPG militia has been highly effective in the war against Islamic State, a part of the wider Syrian conflict pitting a range of insurgent groups against President Bashar al-Assad's forces and sometimes against each other.

But Turkey has long castigated Washington for its military relationship with the YPG. Ankara regards the YPG an extension of the PKK, a Kurdish armed group that has waged an insurgency in southeast Turkey for over three decades.

"PRESIDENT'S REQUIREMENT"

"We don't think the Turks ought to undertake military action that's not fully coordinated with and agreed to by the United States at a minimum," Bolton said, "so they don't endanger our troops, but also so that they meet the president's requirement that the Syrian opposition forces that have fought with us are not endangered."

The YPG has indicated that it might seek a deal with Damascus after the US forces have gone.

Bolton, who will travel to Turkey on Monday, said the United States would talk to Ankara to find out what its objectives and capabilities were.

Erdogan's spokesman Ibrahim Kalin said Turkey's targets were the YPG, the PKK and Islamic State.

"One aim of Turkey's fight against the PKK and its Syrian extensions is to rescue the Kurds from the cruelty and oppression of this terrorist group," state-owned Anadolu news agency quoted Kalin as saying, in comments that emerged after Bolton made his remarks.

"Turkey will continue decisively its efforts to end the war, provide security, and implement the process of political transition without discriminating between our Syrian brothers on the basis of religion, ethnicity or sect," Kalin said.

In Washington on Sunday, Trump reiterated that the United States would be pulling its troops out of Syria but suggested the move might not happen soon.

"I never said we are doing it that quickly. But we are decimating ISIS," Trump told reporters.

Later on Sunday Bolton met with Israeli Prime Minister Benjamin Netanyahu and reassured Israel and other allies of the United States' commitment to their security.

Reuters