WASHINGTON • President Donald Trump's national security adviser, Mr John Bolton, has rolled back Mr Trump's decision to rapidly withdraw from Syria, laying out conditions for a pullout that could leave US forces there for months or even years.

Mr Bolton, making a visit to Israel, told reporters that US forces would remain in Syria until the last remnants of the Islamic State in Iraq and Syria (ISIS) group were defeated and Turkey provided guarantees that it would not strike Kurdish forces allied with the United States.

He and other top White House advisers have led a behind-the-scenes effort to slow Mr Trump's order and reassure allies, including Israel.

"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, so they don't endanger our troops," Mr Bolton said in Jerusalem, where he was travelling before a visit today to Turkey.

Mr Bolton's comments inserted into Mr Trump's strategy something that the President had omitted when he announced on Dec 19 that the United States would depart within 30 days: Any conditions that must be met before the pullout.

The remarks also reflected the disarray that has surrounded the President's decision, which took his staff and foreign allies by surprise and drew objections from the Pentagon that it was logistically impossible and strategically unwise.

Defence Secretary James Mattis resigned within hours of the announcement, and the Pentagon chief of staff, Mr Kevin Sweeney, said last Saturday evening that he was also leaving.

While Mr Bolton said on Sunday that he expected US forces to eventually leave north-eastern Syria, where most of the 2,000 troops in the country are based for the mission against ISIS, he began to lay out an argument for keeping some troops at a garrison in the south-east that is used to monitor the flow of Iranian arms and soldiers.

The move to reverse course on Mr Trump's promised swift withdrawal picked up in recent days even as Mr Bolton worked to avoid openly confronting the President the way Mr Mattis did.

Asked about the shifting timeline on Sunday as he left the White House for meetings about border security at Camp David, Mr Trump told reporters that he had "never said we were doing it that quickly".

In a video on the evening of his announcement last month, he had said that "our boys, our young women, our men - they're all coming back, and they're coming back now", though he later extended that to four months.

Now, the four-month schedule appears highly in doubt.

The conditions Mr Bolton described, including the complete defeat of ISIS and the guarantees from Turkey, could easily stretch out.

Mr Bolton will meet Turkish President Recep Tayyip Erdogan today. Turkey's leader argued with Mr Trump in a phone call last month that ISIS had been defeated, and that US troops were therefore no longer needed to aid Kurdish fighters.

NYTIMES